# Thread size reference: UNC / UNF and ISO metric coarse / fine — major, minor and pitch diameter, tap drill, clearance hole (close, normal, loose)

> What tap drill and clearance hole do I use for a #6-32, 1/4-20, M3, M5 or M8 thread, and what are its minor and pitch diameters?

- Category: Hardware › Fasteners
- Kind: Standard part
- Basis: Tap drills: Mutual Screw & Supply's and East Tennessee State University's UNC / UNF charts (agree), Engineering ToolBox's metric-rounded tap drills, Optimas' ISO metric coarse and fine tapping sizes; clearance holes: Albany County Fasteners' chart (inch close / normal / loose and ISO 273), Optimas and Engineering ToolBox for metric; minor and pitch diameters computed from the 60° basic profile; numbers only
- Page: https://xemstudio.com/objects/thread-reference-tap-drills-clearance/ · JSON: https://xemstudio.com/api/geometry?object=thread-reference-tap-drills-clearance · Plain text: https://xemstudio.com/objects/thread-reference-tap-drills-clearance/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); files CC BY 4.0 or their publisher's license
- Use in every chat: add https://xemstudio.com/mcp as a connector (https://xemstudio.com/use-with-ai/)

**Exact dimensions.** Every file is drawn at true size with no tolerance added. The holes and pins that meet another part are listed below under Mating features, with the fit each joint needs; open those by your process's clearance before making the part.

## Notes

- Series: UNC (coarse) and UNF (fine) per ASME B1.1, #0 to 1-1/2, and ISO metric coarse M1 to M64 and fine-pitch rows M2 to M56 per ISO 261 / ISO 724. Major diameter is the nominal size; pitch is 25.4 / TPI for inch threads. 47 inch rows (UNC and UNF) and the metric rows are listed; #0 exists only in UNF (0-80) and UNC has no #0.
- Computed columns: the basic minor diameter D1 = d - 1.0825 P (the internal thread minor, ISO 68-1 and ASME B1.1 basic profile) and the basic pitch diameter d2 = d - 0.6495 P, both from the major diameter and the pitch; they are basic values, not the limits of a thread class (2A / 2B, 6g / 6H). A tap drill sits between the minor diameter and the major, about 75 % thread.
- Inch tap drills: Mutual Screw's and ETSU's charts agree on every UNC and UNF size they both list (for example #6-32 #36 0.1065 in, 1/4-20 #7 0.2010, 3/8-16 5/16, 1/2-13 27/64) except #0-80 (3/64 = 0.0469 in in ETSU, #56 = 0.0465 in in Mutual Screw; both shown) and ETSU's last row, which is 1-14 UNF, not 1-12 (not used). 5/8-11 reads 0.5312 in in ETSU and 0.5313 in Mutual (rounding; 17/32). Engineering ToolBox gives tap drills in rounded metric sizes (mm) that differ a little from the decimal-inch drills, for example #4-40 2.35 mm against #43 (2.26 mm); both are shown. The two drill charts do not list UNC 1-3/8 or UNF 1-1/8 and up; only Engineering ToolBox's metric tap drill is shown for those.
- Metric tap drills: Optimas' coarse table and Engineering ToolBox's table agree for M5 4.2, M6 5, M8 6.75, M10 8.5, M16 14, M20 17.5, M24 21 and M30 26.5; they differ at M12 (Optimas 10.2, Engineering ToolBox 10.25). Fine-pitch tap drills in Optimas' table equal the major diameter minus the pitch (for example M8 x 1 gives 7, M10 x 1.25 gives 8.75). Nothing in the sources states a thread-percentage for either.
- Clearance holes disagree between sources, so all are shown. Inch: Albany County Fasteners' chart gives a close, normal and loose drill per size (#0 to 1 in); Mutual Screw's chart gives one clearance drill per size (1/4 in: F 0.2570 in, the same as Albany's close fit; #6: #25 0.1495, Albany's normal). ASME B18.2.8 is the standard these close / normal / loose fits come from but neither chart names it, so the standard is not cited as their source. Metric: Albany's chart heads the columns ISO 273 close (H12), normal (H13), loose (H14); Optimas and Engineering ToolBox call them close / medium / free (fine / medium / coarse). They agree for M1.6, M4, M5, M8, M10, M20 and M24 but differ at M2 medium (2.4 in Albany and Optimas, 2.25 in Engineering ToolBox), M3 medium (3.4 against 3.35), M6 medium (6.6 against 6.5), M30 medium (33 in Albany and Optimas, 32 in Engineering ToolBox), M12 (medium 13.5 in Albany, 14 in Optimas and Engineering ToolBox; coarse 14.5 against 15), M14 and M16 (medium and coarse 15.5 / 16.5 and 17.5 / 18.5 in Albany; 16 / 17 and 18 / 19 in Optimas). The ISO 273 standard itself (listed at iso.org) was not read; check it for the values your drawing needs.
- No files: a plain cylinder at the major diameter and a tap-drill hole are plain primitives. Per-size screw and nut models: socket-head-cap-screws-inch-full, machine-screws-inch-asme-b18-6-3, hex-nuts-inch, hex-bolts-inch and the metric screw pages.

## Mating features (exact size; open press / slide / run / socket by your process clearance, leave designed and clamp as drawn)

| feature | exact | mates with | fit | files |
|---|---|---|---|---|
| tapped hole, UNC / UNF | tap drill: #6-32 #36 0.1065 in, #8-32 #29 0.1360, #10-24 #25 0.1495, #10-32 #21 0.1590, 1/4-20 #7 0.2010, 5/16-18 F 0.2570, 3/8-16 5/16 0.3125, 1/2-13 27/64 0.4219 in | screw of the same thread (plain cylinder at the major diameter in the Xem files) | designed | all |
| clearance hole, inch (close / normal / loose) | #6 #27 / #25 / #18 (0.1440 / 0.1495 / 0.1695 in); 1/4 F / 17/64 / 9/32 (0.2570 / 0.2656 / 0.2812 in) | screw shank of the nominal size | slide | all |
| tapped hole, ISO metric coarse | tap drill: M3 2.5, M4 3.3, M5 4.2, M6 5, M8 6.75, M10 8.5, M12 10.2 (10.25 in Engineering ToolBox) mm | screw of the same thread | designed | all |
| clearance hole, ISO metric (close H12 / normal H13 / loose H14) | M3 3.2 / 3.4 / 3.6, M4 4.3 / 4.5 / 4.8, M5 5.3 / 5.5 / 5.8, M6 6.4 / 6.6 / 7, M8 8.4 / 9 / 10, M10 10.5 / 11 / 12 mm (Albany; Optimas and Engineering ToolBox differ at M12 and above and at some medium values) | screw shank of the nominal size | slide | all |

## Sizes

| series | size | pitch / TPI | major diameter | minor diameter D1 (computed) | pitch diameter d2 (computed) | tap drill | tap drill, second source | clearance hole: close / normal / loose (Albany; ISO 273 for metric) | clearance hole, other source 1 | clearance hole, other source 2 |
|---|---|---|---|---|---|---|---|---|---|---|
| UNC (coarse) | #1 | 64 TPI (pitch 0.397 mm) | 0.0730 in (1.854 mm) | 0.0561 in (1.425 mm) | 0.0629 in (1.596 mm) | #53 (0.0595 in) | 1.50 mm | close #48 (0.0760); normal #46 (0.0810); loose #43 (0.0890) in | #47 (0.0785 in) | — |
| UNC (coarse) | #2 | 56 TPI (pitch 0.454 mm) | 0.0860 in (2.184 mm) | 0.0667 in (1.693 mm) | 0.0744 in (1.890 mm) | #50 (0.0700 in) | 1.80 mm | close #43 (0.0890); normal #41 (0.0960); loose #37 (0.1040) in | #42 (0.0935 in) | — |
| UNC (coarse) | #3 | 48 TPI (pitch 0.529 mm) | 0.0990 in (2.515 mm) | 0.0764 in (1.942 mm) | 0.0855 in (2.171 mm) | #47 (0.0785 in) | 2.10 mm | close #38 (0.1015); normal #36 (0.1065); loose #32 (0.1160) in | #37 (0.1040 in) | — |
| UNC (coarse) | #4 | 40 TPI (pitch 0.635 mm) | 0.1120 in (2.845 mm) | 0.0849 in (2.157 mm) | 0.0958 in (2.432 mm) | #43 (0.0890 in) | 2.35 mm | close #32 (0.1160); normal #30 (0.1285); loose #27 (0.1440) in | #31 (0.1200 in) | — |
| UNC (coarse) | #5 | 40 TPI (pitch 0.635 mm) | 0.1250 in (3.175 mm) | 0.0979 in (2.488 mm) | 0.1088 in (2.763 mm) | #38 (0.1015 in) | 2.65 mm | close #30 (0.1285); normal #29 (0.1360); loose #23 (0.1540) in | #29 (0.1360 in) | — |
| UNC (coarse) | #6 | 32 TPI (pitch 0.794 mm) | 0.1380 in (3.505 mm) | 0.1042 in (2.646 mm) | 0.1177 in (2.990 mm) | #36 (0.1065 in) | 2.85 mm | close #27 (0.1440); normal #25 (0.1495); loose #18 (0.1695) in | #25 (0.1495 in) | — |
| UNC (coarse) | #8 | 32 TPI (pitch 0.794 mm) | 0.1640 in (4.166 mm) | 0.1302 in (3.306 mm) | 0.1437 in (3.650 mm) | #29 (0.1360 in) | 3.50 mm | close #18 (0.1695); normal #15 (0.1800); loose #10 (0.1935) in | #16 (0.1770 in) | — |
| UNC (coarse) | #10 | 24 TPI (pitch 1.058 mm) | 0.1900 in (4.826 mm) | 0.1449 in (3.680 mm) | 0.1629 in (4.139 mm) | #25 (0.1495 in) | 4.00 mm | close #9 (0.1960); normal #5 (0.2055); loose #2 (0.2210) in | #9 (0.1960 in) | — |
| UNC (coarse) | #12 | 24 TPI (pitch 1.058 mm) | 0.2160 in (5.486 mm) | 0.1709 in (4.341 mm) | 0.1889 in (4.799 mm) | #16 (0.1770 in) | 4.65 mm | close #2 (0.2210); normal 7/32 (0.2344); loose 1/4 (0.2500) in | #2 (0.2210 in) | — |
| UNC (coarse) | 1/4 | 20 TPI (pitch 1.270 mm) | 0.2500 in (6.350 mm) | 0.1959 in (4.975 mm) | 0.2175 in (5.525 mm) | #7 (0.2010 in) | 5.35 mm | close F (0.2570); normal 17/64 (0.2656); loose 9/32 (0.2812) in | F (0.2570 in) | — |
| UNC (coarse) | 5/16 | 18 TPI (pitch 1.411 mm) | 0.3125 in (7.938 mm) | 0.2524 in (6.410 mm) | 0.2764 in (7.021 mm) | F (0.2570 in) | 6.80 mm | close 21/64 (0.3281); normal 11/32 (0.3438); loose 3/8 (0.3750) in | Q (0.3320 in) | — |
| UNC (coarse) | 3/8 | 16 TPI (pitch 1.587 mm) | 0.3750 in (9.525 mm) | 0.3073 in (7.806 mm) | 0.3344 in (8.494 mm) | 5/16 (0.3125 in) | 8.25 mm | close 25/64 (0.3906); normal 13/32 (0.4062); loose 7/16 (0.4375) in | W (0.3860 in) | — |
| UNC (coarse) | 7/16 | 14 TPI (pitch 1.814 mm) | 0.4375 in (11.112 mm) | 0.3602 in (9.148 mm) | 0.3911 in (9.934 mm) | U (0.3680 in) | 9.65 mm | close 29/64 (0.4531); normal 15/32 (0.4688); loose 1/2 (0.5000) in | 29/64 (0.4531 in) | — |
| UNC (coarse) | 1/2 | 13 TPI (pitch 1.954 mm) | 0.5000 in (12.700 mm) | 0.4167 in (10.585 mm) | 0.4500 in (11.431 mm) | 27/64 (0.4219 in) | 11.15 mm | close 33/64 (0.5156); normal 17/32 (0.5312); loose 9/16 (0.5625) in | 33/64 (0.5156 in) | — |
| UNC (coarse) | 9/16 | 12 TPI (pitch 2.117 mm) | 0.5625 in (14.287 mm) | 0.4723 in (11.996 mm) | 0.5084 in (12.913 mm) | 31/64 (0.4844 in) | 12.60 mm | close 37/64 (0.5781); normal 19/32 (0.5938); loose 5/8 (0.6250) in | 37/64 (0.5781 in) | — |
| UNC (coarse) | 5/8 | 11 TPI (pitch 2.309 mm) | 0.6250 in (15.875 mm) | 0.5266 in (13.375 mm) | 0.5660 in (14.375 mm) | 17/32 (0.5312 in) | 14.05 mm | close 41/64 (0.6406); normal 21/32 (0.6562); loose 11/16 (0.6875) in | 41/64 (0.6406 in) | — |
| UNC (coarse) | 3/4 | 10 TPI (pitch 2.540 mm) | 0.7500 in (19.050 mm) | 0.6417 in (16.300 mm) | 0.6850 in (17.400 mm) | 21/32 (0.6562 in) | 17.00 mm | close 49/64 (0.7656); normal 25/32 (0.7812); loose 13/16 (0.8125) in | 49/64 (0.7656 in) | — |
| UNC (coarse) | 7/8 | 9 TPI (pitch 2.822 mm) | 0.8750 in (22.225 mm) | 0.7547 in (19.170 mm) | 0.8028 in (20.392 mm) | 49/64 (0.7656 in) | 20.00 mm | close 57/64 (0.8906); normal 29/32 (0.9062); loose 15/16 (0.9375) in | 57/64 (0.8906 in) | — |
| UNC (coarse) | 1 | 8 TPI (pitch 3.175 mm) | 1.0000 in (25.400 mm) | 0.8647 in (21.963 mm) | 0.9188 in (23.338 mm) | 7/8 (0.8750 in) | 22.85 mm | close 1-1/64 (1.0156); normal 1-1/32 (1.0312); loose 1-1/16 (1.0625) in | 1-1/64 (1.0156 in) | — |
| UNC (coarse) | 1-1/8 | 7 TPI (pitch 3.629 mm) | 1.1250 in (28.575 mm) | 0.9704 in (24.647 mm) | 1.0322 in (26.218 mm) | 63/64 (0.9844 in) | 25.65 mm | — | 1-9/64 (1.1406 in) | — |
| UNC (coarse) | 1-1/4 | 7 TPI (pitch 3.629 mm) | 1.2500 in (31.750 mm) | 1.0954 in (27.822 mm) | 1.1572 in (29.393 mm) | 1-7/64 (1.1094 in) | 28.85 mm | — | 1-17/64 (1.2656 in) | — |
| UNC (coarse) | 1-3/8 | 6 TPI (pitch 4.233 mm) | 1.3750 in (34.925 mm) | 1.1946 in (30.342 mm) | 1.2667 in (32.175 mm) | — (not in the two drill charts read) (— in) | 31.55 mm | — | — | — |
| UNC (coarse) | 1-1/2 | 6 TPI (pitch 4.233 mm) | 1.5000 in (38.100 mm) | 1.3196 in (33.517 mm) | 1.3917 in (35.350 mm) | 1-11/32 (1.3438 in) | 34.70 mm | — | 1-33/64 (1.5156 in) | — |
| UNF (fine) | #0 | 80 TPI (pitch 0.318 mm) | 0.0600 in (1.524 mm) | 0.0465 in (1.180 mm) | 0.0519 in (1.318 mm) | #56 (Mutual) / 3/64 (ETSU) (0.0465 / 0.0469 in) | 1.25 mm | close #52 (0.0635); normal #50 (0.0700); loose #46 (0.0810) in | #51 (0.0670 in) | — |
| UNF (fine) | #1 | 72 TPI (pitch 0.353 mm) | 0.0730 in (1.854 mm) | 0.0580 in (1.472 mm) | 0.0640 in (1.625 mm) | #53 (0.0595 in) | 1.55 mm | close #48 (0.0760); normal #46 (0.0810); loose #43 (0.0890) in | #47 (0.0785 in) | — |
| UNF (fine) | #2 | 64 TPI (pitch 0.397 mm) | 0.0860 in (2.184 mm) | 0.0691 in (1.755 mm) | 0.0759 in (1.927 mm) | #50 (0.0700 in) | 1.90 mm | close #43 (0.0890); normal #41 (0.0960); loose #37 (0.1040) in | #42 (0.0935 in) | — |
| UNF (fine) | #3 | 56 TPI (pitch 0.454 mm) | 0.0990 in (2.515 mm) | 0.0797 in (2.024 mm) | 0.0874 in (2.220 mm) | #45 (0.0820 in) | 2.15 mm | close #38 (0.1015); normal #36 (0.1065); loose #32 (0.1160) in | #37 (0.1040 in) | — |
| UNF (fine) | #4 | 48 TPI (pitch 0.529 mm) | 0.1120 in (2.845 mm) | 0.0894 in (2.272 mm) | 0.0985 in (2.501 mm) | #42 (0.0935 in) | 2.40 mm | close #32 (0.1160); normal #30 (0.1285); loose #27 (0.1440) in | #31 (0.1200 in) | — |
| UNF (fine) | #5 | 44 TPI (pitch 0.577 mm) | 0.1250 in (3.175 mm) | 0.1004 in (2.550 mm) | 0.1102 in (2.800 mm) | #37 (0.1040 in) | 2.70 mm | close #30 (0.1285); normal #29 (0.1360); loose #23 (0.1540) in | #29 (0.1360 in) | — |
| UNF (fine) | #6 | 40 TPI (pitch 0.635 mm) | 0.1380 in (3.505 mm) | 0.1109 in (2.818 mm) | 0.1218 in (3.093 mm) | #33 (0.1130 in) | 2.95 mm | close #27 (0.1440); normal #25 (0.1495); loose #18 (0.1695) in | #25 (0.1495 in) | — |
| UNF (fine) | #8 | 36 TPI (pitch 0.706 mm) | 0.1640 in (4.166 mm) | 0.1339 in (3.402 mm) | 0.1460 in (3.707 mm) | #29 (0.1360 in) | 3.50 mm | close #18 (0.1695); normal #15 (0.1800); loose #10 (0.1935) in | #16 (0.1770 in) | — |
| UNF (fine) | #10 | 32 TPI (pitch 0.794 mm) | 0.1900 in (4.826 mm) | 0.1562 in (3.967 mm) | 0.1697 in (4.310 mm) | #21 (0.1590 in) | 4.10 mm | close #9 (0.1960); normal #5 (0.2055); loose #2 (0.2210) in | #9 (0.1960 in) | — |
| UNF (fine) | #12 | 28 TPI (pitch 0.907 mm) | 0.2160 in (5.486 mm) | 0.1773 in (4.504 mm) | 0.1928 in (4.897 mm) | #14 (0.1820 in) | 4.70 mm | close #2 (0.2210); normal 7/32 (0.2344); loose 1/4 (0.2500) in | #2 (0.2210 in) | — |
| UNF (fine) | 1/4 | 28 TPI (pitch 0.907 mm) | 0.2500 in (6.350 mm) | 0.2113 in (5.368 mm) | 0.2268 in (5.761 mm) | #3 (0.2130 in) | 5.50 mm | close F (0.2570); normal 17/64 (0.2656); loose 9/32 (0.2812) in | F (0.2570 in) | — |
| UNF (fine) | 5/16 | 24 TPI (pitch 1.058 mm) | 0.3125 in (7.938 mm) | 0.2674 in (6.792 mm) | 0.2854 in (7.250 mm) | I (0.2720 in) | 6.90 mm | close 21/64 (0.3281); normal 11/32 (0.3438); loose 3/8 (0.3750) in | Q (0.3320 in) | — |
| UNF (fine) | 3/8 | 24 TPI (pitch 1.058 mm) | 0.3750 in (9.525 mm) | 0.3299 in (8.379 mm) | 0.3479 in (8.838 mm) | Q (0.3320 in) | 8.50 mm | close 25/64 (0.3906); normal 13/32 (0.4062); loose 7/16 (0.4375) in | W (0.3860 in) | — |
| UNF (fine) | 7/16 | 20 TPI (pitch 1.270 mm) | 0.4375 in (11.112 mm) | 0.3834 in (9.738 mm) | 0.4050 in (10.288 mm) | 25/64 (0.3906 in) | 9.90 mm | close 29/64 (0.4531); normal 15/32 (0.4688); loose 1/2 (0.5000) in | 29/64 (0.4531 in) | — |
| UNF (fine) | 1/2 | 20 TPI (pitch 1.270 mm) | 0.5000 in (12.700 mm) | 0.4459 in (11.325 mm) | 0.4675 in (11.875 mm) | 29/64 (0.4531 in) | 11.50 mm | close 33/64 (0.5156); normal 17/32 (0.5312); loose 9/16 (0.5625) in | 33/64 (0.5156 in) | — |
| UNF (fine) | 9/16 | 18 TPI (pitch 1.411 mm) | 0.5625 in (14.287 mm) | 0.5024 in (12.760 mm) | 0.5264 in (13.371 mm) | 33/64 (0.5156 in) | 12.90 mm | close 37/64 (0.5781); normal 19/32 (0.5938); loose 5/8 (0.6250) in | 37/64 (0.5781 in) | — |
| UNF (fine) | 5/8 | 18 TPI (pitch 1.411 mm) | 0.6250 in (15.875 mm) | 0.5649 in (14.347 mm) | 0.5889 in (14.958 mm) | 37/64 (0.5781 in) | 14.50 mm | close 41/64 (0.6406); normal 21/32 (0.6562); loose 11/16 (0.6875) in | 41/64 (0.6406 in) | — |
| UNF (fine) | 3/4 | 16 TPI (pitch 1.587 mm) | 0.7500 in (19.050 mm) | 0.6823 in (17.331 mm) | 0.7094 in (18.019 mm) | 11/16 (0.6875 in) | 17.50 mm | close 49/64 (0.7656); normal 25/32 (0.7812); loose 13/16 (0.8125) in | 49/64 (0.7656 in) | — |
| UNF (fine) | 7/8 | 14 TPI (pitch 1.814 mm) | 0.8750 in (22.225 mm) | 0.7977 in (20.261 mm) | 0.8286 in (21.047 mm) | 13/16 (0.8125 in) | 20.40 mm | close 57/64 (0.8906); normal 29/32 (0.9062); loose 15/16 (0.9375) in | 57/64 (0.8906 in) | — |
| UNF (fine) | 1 | 12 TPI (pitch 2.117 mm) | 1.0000 in (25.400 mm) | 0.9098 in (23.109 mm) | 0.9459 in (24.025 mm) | 59/64 (0.9219 in) | 23.25 mm | close 1-1/64 (1.0156); normal 1-1/32 (1.0312); loose 1-1/16 (1.0625) in | 1-1/64 (1.0156 in) | — |
| UNF (fine) | 1-1/8 | 12 TPI (pitch 2.117 mm) | 1.1250 in (28.575 mm) | 1.0348 in (26.284 mm) | 1.0709 in (27.200 mm) | — (not in the two drill charts read) (— in) | 26.50 mm | — | 1-9/64 (1.1406 in) | — |
| UNF (fine) | 1-1/4 | 12 TPI (pitch 2.117 mm) | 1.2500 in (31.750 mm) | 1.1598 in (29.459 mm) | 1.1959 in (30.375 mm) | — (not in the two drill charts read) (— in) | 29.50 mm | — | 1-17/64 (1.2656 in) | — |
| UNF (fine) | 1-3/8 | 12 TPI (pitch 2.117 mm) | 1.3750 in (34.925 mm) | 1.2848 in (32.634 mm) | 1.3209 in (33.550 mm) | — (not in the two drill charts read) (— in) | 32.75 mm | — | — | — |
| UNF (fine) | 1-1/2 | 12 TPI (pitch 2.117 mm) | 1.5000 in (38.100 mm) | 1.4098 in (35.809 mm) | 1.4459 in (36.725 mm) | — (not in the two drill charts read) (— in) | 36.00 mm | — | 1-33/64 (1.5156 in) | — |
| ISO metric coarse | M1 | 0.25 mm | 1 mm | 0.729 mm | 0.838 mm | 0.75 mm (Optimas) | — | — | close — / medium 1.2 / free — mm (Optimas) | — |
| ISO metric coarse | M1.1 | 0.25 mm | 1.1 mm | 0.829 mm | 0.938 mm | 0.85 mm (Optimas) | — | — | — | — |
| ISO metric coarse | M1.2 | 0.25 mm | 1.2 mm | 0.929 mm | 1.038 mm | 0.95 mm (Optimas) | — | — | close — / medium 1.4 / free — mm (Optimas) | — |
| ISO metric coarse | M1.4 | 0.3 mm | 1.4 mm | 1.075 mm | 1.205 mm | 1.1 mm (Optimas) | — | — | close — / medium 1.6 / free — mm (Optimas) | — |
| ISO metric coarse | M1.6 | 0.35 mm | 1.6 mm | 1.221 mm | 1.373 mm | 1.25 mm (Optimas) | — | ISO 273 close H12 1.7 / normal H13 1.8 / loose H14 2.0 mm (Albany) | close 1.7 / medium 1.8 / free 2 mm (Optimas) | fine 1.7 / medium 1.8 / coarse 2 mm (Engineering ToolBox) |
| ISO metric coarse | M1.8 | 0.35 mm | 1.8 mm | 1.421 mm | 1.573 mm | 1.45 mm (Optimas) | — | — | close — / medium 2 / free — mm (Optimas) | — |
| ISO metric coarse | M2 | 0.4 mm | 2 mm | 1.567 mm | 1.740 mm | 1.6 mm (Optimas) | — | ISO 273 close H12 2.2 / normal H13 2.4 / loose H14 2.6 mm (Albany) | close 2.2 / medium 2.4 / free 2.6 mm (Optimas) | fine 2.2 / medium 2.25 / coarse 2.6 mm (Engineering ToolBox) |
| ISO metric coarse | M2.2 | 0.45 mm | 2.2 mm | 1.713 mm | 1.908 mm | 1.75 mm (Optimas) | — | — | close — / medium 2.8 / free — mm (Optimas) | — |
| ISO metric coarse | M2.5 | 0.45 mm | 2.5 mm | 2.013 mm | 2.208 mm | 2.05 mm (Optimas) | — | ISO 273 close H12 2.7 / normal H13 2.9 / loose H14 3.1 mm (Albany) | close 2.7 / medium 2.9 / free 3.1 mm (Optimas) | fine 2.7 / medium 2.8 / coarse 3.1 mm (Engineering ToolBox) |
| ISO metric coarse | M3 | 0.5 mm | 3 mm | 2.459 mm | 2.675 mm | 2.5 mm (Optimas) | — | ISO 273 close H12 3.2 / normal H13 3.4 / loose H14 3.6 mm (Albany) | close 3.2 / medium 3.4 / free 3.6 mm (Optimas) | fine 3.2 / medium 3.35 / coarse 3.6 mm (Engineering ToolBox) |
| ISO metric coarse | M3.5 | 0.6 mm | 3.5 mm | 2.850 mm | 3.110 mm | 2.9 mm (Optimas) | — | — | close — / medium 3.9 / free — mm (Optimas) | — |
| ISO metric coarse | M4 | 0.7 mm | 4 mm | 3.242 mm | 3.545 mm | 3.3 mm (Optimas) | — | ISO 273 close H12 4.3 / normal H13 4.5 / loose H14 4.8 mm (Albany) | close 4.3 / medium 4.5 / free 4.8 mm (Optimas) | fine 4.3 / medium 4.5 / coarse 4.8 mm (Engineering ToolBox) |
| ISO metric coarse | M4.5 | 0.75 mm | 4.5 mm | 3.688 mm | 4.013 mm | 3.75 mm (Optimas) | — | — | — | — |
| ISO metric coarse | M5 | 0.8 mm | 5 mm | 4.134 mm | 4.480 mm | 4.2 mm (Optimas) | 4.2 mm (Engineering ToolBox) | ISO 273 close H12 5.3 / normal H13 5.5 / loose H14 5.8 mm (Albany) | close 5.3 / medium 5.5 / free 5.8 mm (Optimas) | fine 5.3 / medium 5.5 / coarse 5.8 mm (Engineering ToolBox) |
| ISO metric coarse | M6 | 1 mm | 6 mm | 4.917 mm | 5.350 mm | 5 mm (Optimas) | 5 mm (Engineering ToolBox) | ISO 273 close H12 6.4 / normal H13 6.6 / loose H14 7.0 mm (Albany) | close 6.4 / medium 6.6 / free 7 mm (Optimas) | fine 6.4 / medium 6.5 / coarse 7 mm (Engineering ToolBox) |
| ISO metric coarse | M7 | 1 mm | 7 mm | 5.917 mm | 6.350 mm | 6 mm (Optimas) | — | — | — | — |
| ISO metric coarse | M8 | 1.25 mm | 8 mm | 6.647 mm | 7.188 mm | 6.75 mm (Optimas) | 6.75 mm (Engineering ToolBox) | ISO 273 close H12 8.4 / normal H13 9.0 / loose H14 10.0 mm (Albany) | close 8.4 / medium 9 / free 10 mm (Optimas) | fine 8.4 / medium 9 / coarse 10 mm (Engineering ToolBox) |
| ISO metric coarse | M9 | 1.25 mm | 9 mm | 7.647 mm | 8.188 mm | 7.75 mm (Optimas) | — | — | — | — |
| ISO metric coarse | M10 | 1.5 mm | 10 mm | 8.376 mm | 9.026 mm | 8.5 mm (Optimas) | 8.5 mm (Engineering ToolBox) | ISO 273 close H12 10.5 / normal H13 11.0 / loose H14 12.0 mm (Albany) | close 10.5 / medium 11 / free 12 mm (Optimas) | fine 10.5 / medium 11 / coarse 12 mm (Engineering ToolBox) |
| ISO metric coarse | M11 | 1.5 mm | 11 mm | 9.376 mm | 10.026 mm | 9.5 mm (Optimas) | — | — | — | — |
| ISO metric coarse | M12 | 1.75 mm | 12 mm | 10.106 mm | 10.863 mm | 10.2 mm (Optimas) | 10.25 mm (Engineering ToolBox) | ISO 273 close H12 13.0 / normal H13 13.5 / loose H14 14.5 mm (Albany) | close 13 / medium 14 / free 15 mm (Optimas) | fine 13 / medium 14 / coarse 15 mm (Engineering ToolBox) |
| ISO metric coarse | M14 | 2 mm | 14 mm | 11.835 mm | 12.701 mm | 12 mm (Optimas) | — | ISO 273 close H12 15.0 / normal H13 15.5 / loose H14 16.5 mm (Albany) | close 15 / medium 16 / free 17 mm (Optimas) | — |
| ISO metric coarse | M16 | 2 mm | 16 mm | 13.835 mm | 14.701 mm | 14 mm (Optimas) | 14 mm (Engineering ToolBox) | ISO 273 close H12 17.0 / normal H13 17.5 / loose H14 18.5 mm (Albany) | close 17 / medium 18 / free 19 mm (Optimas) | fine 17 / medium 18 / coarse 19 mm (Engineering ToolBox) |
| ISO metric coarse | M18 | 2.5 mm | 18 mm | 15.294 mm | 16.376 mm | 15.5 mm (Optimas) | — | — | close 19 / medium 20 / free 21 mm (Optimas) | — |
| ISO metric coarse | M20 | 2.5 mm | 20 mm | 17.294 mm | 18.376 mm | 17.5 mm (Optimas) | 17.5 mm (Engineering ToolBox) | ISO 273 close H12 21.0 / normal H13 22.0 / loose H14 24.0 mm (Albany) | close 21 / medium 22 / free 24 mm (Optimas) | fine 21 / medium 22 / coarse 24 mm (Engineering ToolBox) |
| ISO metric coarse | M22 | 2.5 mm | 22 mm | 19.294 mm | 20.376 mm | 19.5 mm (Optimas) | — | — | close 23 / medium 24 / free 26 mm (Optimas) | — |
| ISO metric coarse | M24 | 3 mm | 24 mm | 20.752 mm | 22.051 mm | 21 mm (Optimas) | 21 mm (Engineering ToolBox) | ISO 273 close H12 25.0 / normal H13 26.0 / loose H14 28.0 mm (Albany) | close 25 / medium 26 / free 28 mm (Optimas) | fine 25 / medium 26 / coarse 28 mm (Engineering ToolBox) |
| ISO metric coarse | M27 | 3 mm | 27 mm | 23.752 mm | 25.051 mm | 24 mm (Optimas) | — | — | close 28 / medium 30 / free 32 mm (Optimas) | — |
| ISO metric coarse | M30 | 3.5 mm | 30 mm | 26.211 mm | 27.727 mm | 26.5 mm (Optimas) | 26.5 mm (Engineering ToolBox) | ISO 273 close H12 31.0 / normal H13 33.0 / loose H14 35.0 mm (Albany) | close 31 / medium 33 / free 35 mm (Optimas) | fine 31 / medium 32 / coarse 35 mm (Engineering ToolBox) |
| ISO metric coarse | M33 | 3.5 mm | 33 mm | 29.211 mm | 30.727 mm | 29.5 mm (Optimas) | — | — | close 34 / medium 36 / free 38 mm (Optimas) | — |
| ISO metric coarse | M36 | 4 mm | 36 mm | 31.670 mm | 33.402 mm | 32 mm (Optimas) | — | — | close 37 / medium 39 / free 42 mm (Optimas) | — |
| ISO metric coarse | M39 | 4 mm | 39 mm | 34.670 mm | 36.402 mm | 35 mm (Optimas) | — | — | close 40 / medium 42 / free 45 mm (Optimas) | — |
| ISO metric coarse | M42 | 4.5 mm | 42 mm | 37.129 mm | 39.077 mm | 37.5 mm (Optimas) | — | — | close 43 / medium 45 / free 48 mm (Optimas) | — |
| ISO metric coarse | M45 | 4.5 mm | 45 mm | 40.129 mm | 42.077 mm | 40.5 mm (Optimas) | — | — | close 46 / medium 48 / free 52 mm (Optimas) | — |
| ISO metric coarse | M48 | 5 mm | 48 mm | 42.587 mm | 44.752 mm | 43 mm (Optimas) | — | — | close 50 / medium 52 / free 56 mm (Optimas) | — |
| ISO metric coarse | M52 | 5 mm | 52 mm | 46.587 mm | 48.752 mm | 47 mm (Optimas) | — | — | close 54 / medium 56 / free 62 mm (Optimas) | — |
| ISO metric coarse | M56 | 5.5 mm | 56 mm | 50.046 mm | 52.428 mm | 50.5 mm (Optimas) | — | — | — | — |
| ISO metric coarse | M60 | 5.5 mm | 60 mm | 54.046 mm | 56.428 mm | 54.5 mm (Optimas) | — | — | — | — |
| ISO metric coarse | M64 | 6 mm | 64 mm | 57.505 mm | 60.103 mm | 58 mm (Optimas) | — | — | — | — |
| ISO metric fine | M2 | 0.25 mm | 2 mm | 1.729 mm | 1.838 mm | 1.75 mm (Optimas) | — | — | — | — |
| ISO metric fine | M2.2 | 0.25 mm | 2.2 mm | 1.929 mm | 2.038 mm | 1.95 mm (Optimas) | — | — | — | — |
| ISO metric fine | M2.3 | 0.25 mm | 2.3 mm | 2.029 mm | 2.138 mm | 2.05 mm (Optimas) | — | — | — | — |
| ISO metric fine | M2.5 | 0.35 mm | 2.5 mm | 2.121 mm | 2.273 mm | 2.15 mm (Optimas) | — | — | — | — |
| ISO metric fine | M2.6 | 0.35 mm | 2.6 mm | 2.221 mm | 2.373 mm | 2.25 mm (Optimas) | — | — | — | — |
| ISO metric fine | M3 | 0.35 mm | 3 mm | 2.621 mm | 2.773 mm | 2.65 mm (Optimas) | — | — | — | — |
| ISO metric fine | M3.5 | 0.35 mm | 3.5 mm | 3.121 mm | 3.273 mm | 3.15 mm (Optimas) | — | — | — | — |
| ISO metric fine | M4 | 0.35 mm | 4 mm | 3.621 mm | 3.773 mm | 3.65 mm (Optimas) | — | — | — | — |
| ISO metric fine | M4 | 0.5 mm | 4 mm | 3.459 mm | 3.675 mm | 3.5 mm (Optimas) | — | — | — | — |
| ISO metric fine | M5 | 0.35 mm | 5 mm | 4.621 mm | 4.773 mm | 4.65 mm (Optimas) | — | — | — | — |
| ISO metric fine | M5 | 0.5 mm | 5 mm | 4.459 mm | 4.675 mm | 4.5 mm (Optimas) | — | — | — | — |
| ISO metric fine | M5 | 0.75 mm | 5 mm | 4.188 mm | 4.513 mm | 4.25 mm (Optimas) | — | — | — | — |
| ISO metric fine | M5.5 | 0.5 mm | 5.5 mm | 4.959 mm | 5.175 mm | 5 mm (Optimas) | — | — | — | — |
| ISO metric fine | M6 | 0.5 mm | 6 mm | 5.459 mm | 5.675 mm | 5.5 mm (Optimas) | — | — | — | — |
| ISO metric fine | M6 | 0.75 mm | 6 mm | 5.188 mm | 5.513 mm | 5.25 mm (Optimas) | — | — | — | — |
| ISO metric fine | M7 | 0.75 mm | 7 mm | 6.188 mm | 6.513 mm | 6.25 mm (Optimas) | — | — | — | — |
| ISO metric fine | M8 | 0.5 mm | 8 mm | 7.459 mm | 7.675 mm | 7.5 mm (Optimas) | — | — | — | — |
| ISO metric fine | M8 | 0.75 mm | 8 mm | 7.188 mm | 7.513 mm | 7.25 mm (Optimas) | — | — | — | — |
| ISO metric fine | M8 | 1 mm | 8 mm | 6.917 mm | 7.350 mm | 7 mm (Optimas) | — | — | — | — |
| ISO metric fine | M9 | 0.75 mm | 9 mm | 8.188 mm | 8.513 mm | 8.25 mm (Optimas) | — | — | — | — |
| ISO metric fine | M9 | 1 mm | 9 mm | 7.917 mm | 8.350 mm | 8 mm (Optimas) | — | — | — | — |
| ISO metric fine | M10 | 0.5 mm | 10 mm | 9.459 mm | 9.675 mm | 9.5 mm (Optimas) | — | — | — | — |
| ISO metric fine | M10 | 0.75 mm | 10 mm | 9.188 mm | 9.513 mm | 9.25 mm (Optimas) | — | — | — | — |
| ISO metric fine | M10 | 1 mm | 10 mm | 8.917 mm | 9.350 mm | 9 mm (Optimas) | — | — | — | — |
| ISO metric fine | M10 | 1.25 mm | 10 mm | 8.647 mm | 9.188 mm | 8.75 mm (Optimas) | — | — | — | — |
| ISO metric fine | M11 | 0.75 mm | 11 mm | 10.188 mm | 10.513 mm | 10.25 mm (Optimas) | — | — | — | — |
| ISO metric fine | M11 | 1 mm | 11 mm | 9.917 mm | 10.350 mm | 10 mm (Optimas) | — | — | — | — |
| ISO metric fine | M11 | 1.25 mm | 11 mm | 9.647 mm | 10.188 mm | 9.75 mm (Optimas) | — | — | — | — |
| ISO metric fine | M12 | 0.5 mm | 12 mm | 11.459 mm | 11.675 mm | 11.5 mm (Optimas) | — | — | — | — |
| ISO metric fine | M12 | 0.75 mm | 12 mm | 11.188 mm | 11.513 mm | 11.25 mm (Optimas) | — | — | — | — |
| ISO metric fine | M12 | 1 mm | 12 mm | 10.917 mm | 11.350 mm | 11 mm (Optimas) | — | — | — | — |
| ISO metric fine | M12 | 1.25 mm | 12 mm | 10.647 mm | 11.188 mm | 10.75 mm (Optimas) | — | — | — | — |
| ISO metric fine | M12 | 1.5 mm | 12 mm | 10.376 mm | 11.026 mm | 10.5 mm (Optimas) | — | — | — | — |
| ISO metric fine | M14 | 1 mm | 14 mm | 12.917 mm | 13.350 mm | 13 mm (Optimas) | — | — | — | — |
| ISO metric fine | M14 | 1.25 mm | 14 mm | 12.647 mm | 13.188 mm | 12.75 mm (Optimas) | — | — | — | — |
| ISO metric fine | M14 | 1.5 mm | 14 mm | 12.376 mm | 13.026 mm | 12.5 mm (Optimas) | — | — | — | — |
| ISO metric fine | M15 | 0.75 mm | 15 mm | 14.188 mm | 14.513 mm | 14.25 mm (Optimas) | — | — | — | — |
| ISO metric fine | M15 | 1 mm | 15 mm | 13.917 mm | 14.350 mm | 14 mm (Optimas) | — | — | — | — |
| ISO metric fine | M15 | 1.5 mm | 15 mm | 13.376 mm | 14.026 mm | 13.5 mm (Optimas) | — | — | — | — |
| ISO metric fine | M16 | 0.5 mm | 16 mm | 15.459 mm | 15.675 mm | 15.5 mm (Optimas) | — | — | — | — |
| ISO metric fine | M16 | 0.75 mm | 16 mm | 15.188 mm | 15.513 mm | 15.25 mm (Optimas) | — | — | — | — |
| ISO metric fine | M16 | 1 mm | 16 mm | 14.917 mm | 15.350 mm | 15 mm (Optimas) | — | — | — | — |
| ISO metric fine | M16 | 1.25 mm | 16 mm | 14.647 mm | 15.188 mm | 14.75 mm (Optimas) | — | — | — | — |
| ISO metric fine | M16 | 1.5 mm | 16 mm | 14.376 mm | 15.026 mm | 14.5 mm (Optimas) | — | — | — | — |
| ISO metric fine | M17 | 1 mm | 17 mm | 15.917 mm | 16.350 mm | 16 mm (Optimas) | — | — | — | — |
| ISO metric fine | M17 | 1.5 mm | 17 mm | 15.376 mm | 16.026 mm | 15.5 mm (Optimas) | — | — | — | — |
| ISO metric fine | M18 | 0.75 mm | 18 mm | 17.188 mm | 17.513 mm | 17.25 mm (Optimas) | — | — | — | — |
| ISO metric fine | M18 | 1 mm | 18 mm | 16.917 mm | 17.350 mm | 17 mm (Optimas) | — | — | — | — |
| ISO metric fine | M18 | 1.25 mm | 18 mm | 16.647 mm | 17.188 mm | 16.75 mm (Optimas) | — | — | — | — |
| ISO metric fine | M18 | 1.5 mm | 18 mm | 16.376 mm | 17.026 mm | 16.5 mm (Optimas) | — | — | — | — |
| ISO metric fine | M18 | 2 mm | 18 mm | 15.835 mm | 16.701 mm | 16 mm (Optimas) | — | — | — | — |
| ISO metric fine | M19 | 1 mm | 19 mm | 17.917 mm | 18.350 mm | 18 mm (Optimas) | — | — | — | — |
| ISO metric fine | M20 | 1.5 mm | 20 mm | 18.376 mm | 19.026 mm | 18.5 mm (Optimas) | — | — | — | — |
| ISO metric fine | M20 | 2 mm | 20 mm | 17.835 mm | 18.701 mm | 18 mm (Optimas) | — | — | — | — |
| ISO metric fine | M22 | 1 mm | 22 mm | 20.917 mm | 21.350 mm | 21 mm (Optimas) | — | — | — | — |
| ISO metric fine | M22 | 1.5 mm | 22 mm | 20.376 mm | 21.026 mm | 20.5 mm (Optimas) | — | — | — | — |
| ISO metric fine | M22 | 2 mm | 22 mm | 19.835 mm | 20.701 mm | 20 mm (Optimas) | — | — | — | — |
| ISO metric fine | M24 | 1 mm | 24 mm | 22.917 mm | 23.350 mm | 23 mm (Optimas) | — | — | — | — |
| ISO metric fine | M24 | 1.5 mm | 24 mm | 22.376 mm | 23.026 mm | 22.5 mm (Optimas) | — | — | — | — |
| ISO metric fine | M24 | 2 mm | 24 mm | 21.835 mm | 22.701 mm | 22 mm (Optimas) | — | — | — | — |
| ISO metric fine | M25 | 1 mm | 25 mm | 23.917 mm | 24.350 mm | 24 mm (Optimas) | — | — | — | — |
| ISO metric fine | M25 | 1.5 mm | 25 mm | 23.376 mm | 24.026 mm | 23.5 mm (Optimas) | — | — | — | — |
| ISO metric fine | M25 | 2 mm | 25 mm | 22.835 mm | 23.701 mm | 23 mm (Optimas) | — | — | — | — |
| ISO metric fine | M27 | 1 mm | 27 mm | 25.917 mm | 26.350 mm | 26 mm (Optimas) | — | — | — | — |
| ISO metric fine | M27 | 1.5 mm | 27 mm | 25.376 mm | 26.026 mm | 25.5 mm (Optimas) | — | — | — | — |
| ISO metric fine | M27 | 2 mm | 27 mm | 24.835 mm | 25.701 mm | 25 mm (Optimas) | — | — | — | — |
| ISO metric fine | M28 | 1 mm | 28 mm | 26.917 mm | 27.350 mm | 27 mm (Optimas) | — | — | — | — |
| ISO metric fine | M28 | 1.5 mm | 28 mm | 26.376 mm | 27.026 mm | 26.5 mm (Optimas) | — | — | — | — |
| ISO metric fine | M28 | 2 mm | 28 mm | 25.835 mm | 26.701 mm | 26 mm (Optimas) | — | — | — | — |
| ISO metric fine | M30 | 1 mm | 30 mm | 28.917 mm | 29.350 mm | 29 mm (Optimas) | — | — | — | — |
| ISO metric fine | M30 | 1.5 mm | 30 mm | 28.376 mm | 29.026 mm | 28.5 mm (Optimas) | — | — | — | — |
| ISO metric fine | M30 | 2 mm | 30 mm | 27.835 mm | 28.701 mm | 28 mm (Optimas) | — | — | — | — |
| ISO metric fine | M30 | 3 mm | 30 mm | 26.752 mm | 28.051 mm | 27 mm (Optimas) | — | — | — | — |
| ISO metric fine | M32 | 1 mm | 32 mm | 30.917 mm | 31.350 mm | 31 mm (Optimas) | — | — | — | — |
| ISO metric fine | M32 | 1.5 mm | 32 mm | 30.376 mm | 31.026 mm | 30.5 mm (Optimas) | — | — | — | — |
| ISO metric fine | M32 | 2 mm | 32 mm | 29.835 mm | 30.701 mm | 30 mm (Optimas) | — | — | — | — |
| ISO metric fine | M33 | 1.5 mm | 33 mm | 31.376 mm | 32.026 mm | 31.5 mm (Optimas) | — | — | — | — |
| ISO metric fine | M33 | 2 mm | 33 mm | 30.835 mm | 31.701 mm | 31 mm (Optimas) | — | — | — | — |
| ISO metric fine | M33 | 3 mm | 33 mm | 29.752 mm | 31.051 mm | 30 mm (Optimas) | — | — | — | — |
| ISO metric fine | M35 | 1.5 mm | 35 mm | 33.376 mm | 34.026 mm | 33.5 mm (Optimas) | — | — | — | — |
| ISO metric fine | M35 | 2 mm | 35 mm | 32.835 mm | 33.701 mm | 33 mm (Optimas) | — | — | — | — |
| ISO metric fine | M35 | 3 mm | 35 mm | 31.752 mm | 33.051 mm | 32 mm (Optimas) | — | — | — | — |
| ISO metric fine | M36 | 1 mm | 36 mm | 34.917 mm | 35.350 mm | 35 mm (Optimas) | — | — | — | — |
| ISO metric fine | M36 | 1.5 mm | 36 mm | 34.376 mm | 35.026 mm | 34.4 mm (Optimas) | — | — | — | — |
| ISO metric fine | M36 | 2 mm | 36 mm | 33.835 mm | 34.701 mm | 34 mm (Optimas) | — | — | — | — |
| ISO metric fine | M36 | 3 mm | 36 mm | 32.752 mm | 34.051 mm | 33 mm (Optimas) | — | — | — | — |
| ISO metric fine | M38 | 1 mm | 38 mm | 36.917 mm | 37.350 mm | 37 mm (Optimas) | — | — | — | — |
| ISO metric fine | M38 | 1.5 mm | 38 mm | 36.376 mm | 37.026 mm | 36.5 mm (Optimas) | — | — | — | — |
| ISO metric fine | M38 | 2 mm | 38 mm | 35.835 mm | 36.701 mm | 36 mm (Optimas) | — | — | — | — |
| ISO metric fine | M39 | 1.5 mm | 39 mm | 37.376 mm | 38.026 mm | 37.5 mm (Optimas) | — | — | — | — |
| ISO metric fine | M39 | 2 mm | 39 mm | 36.835 mm | 37.701 mm | 37 mm (Optimas) | — | — | — | — |
| ISO metric fine | M39 | 3 mm | 39 mm | 35.752 mm | 37.051 mm | 36 mm (Optimas) | — | — | — | — |
| ISO metric fine | M40 | 1 mm | 40 mm | 38.917 mm | 39.350 mm | 39 mm (Optimas) | — | — | — | — |
| ISO metric fine | M40 | 1.5 mm | 40 mm | 38.376 mm | 39.026 mm | 38.5 mm (Optimas) | — | — | — | — |
| ISO metric fine | M40 | 3 mm | 40 mm | 36.752 mm | 38.051 mm | 37 mm (Optimas) | — | — | — | — |
| ISO metric fine | M42 | 1.5 mm | 42 mm | 40.376 mm | 41.026 mm | 40.5 mm (Optimas) | — | — | — | — |
| ISO metric fine | M42 | 2 mm | 42 mm | 39.835 mm | 40.701 mm | 40 mm (Optimas) | — | — | — | — |
| ISO metric fine | M42 | 3 mm | 42 mm | 38.752 mm | 40.051 mm | 39 mm (Optimas) | — | — | — | — |
| ISO metric fine | M42 | 4 mm | 42 mm | 37.670 mm | 39.402 mm | 38 mm (Optimas) | — | — | — | — |
| ISO metric fine | M45 | 1.5 mm | 45 mm | 43.376 mm | 44.026 mm | 43.5 mm (Optimas) | — | — | — | — |
| ISO metric fine | M45 | 2 mm | 45 mm | 42.835 mm | 43.701 mm | 43 mm (Optimas) | — | — | — | — |
| ISO metric fine | M45 | 3 mm | 45 mm | 41.752 mm | 43.051 mm | 42 mm (Optimas) | — | — | — | — |
| ISO metric fine | M48 | 1.5 mm | 48 mm | 46.376 mm | 47.026 mm | 46.5 mm (Optimas) | — | — | — | — |
| ISO metric fine | M48 | 2 mm | 48 mm | 45.835 mm | 46.701 mm | 46 mm (Optimas) | — | — | — | — |
| ISO metric fine | M48 | 3 mm | 48 mm | 44.752 mm | 46.051 mm | 45 mm (Optimas) | — | — | — | — |
| ISO metric fine | M48 | 4 mm | 48 mm | 43.670 mm | 45.402 mm | 44 mm (Optimas) | — | — | — | — |
| ISO metric fine | M50 | 1.5 mm | 50 mm | 48.376 mm | 49.026 mm | 48.5 mm (Optimas) | — | — | — | — |
| ISO metric fine | M50 | 2 mm | 50 mm | 47.835 mm | 48.701 mm | 48 mm (Optimas) | — | — | — | — |
| ISO metric fine | M50 | 3 mm | 50 mm | 46.752 mm | 48.051 mm | 47 mm (Optimas) | — | — | — | — |
| ISO metric fine | M52 | 1.5 mm | 52 mm | 50.376 mm | 51.026 mm | 50.5 mm (Optimas) | — | — | — | — |
| ISO metric fine | M52 | 2 mm | 52 mm | 49.835 mm | 50.701 mm | 50 mm (Optimas) | — | — | — | — |
| ISO metric fine | M52 | 3 mm | 52 mm | 48.752 mm | 50.051 mm | 49 mm (Optimas) | — | — | — | — |
| ISO metric fine | M52 | 4 mm | 52 mm | 47.670 mm | 49.402 mm | 48 mm (Optimas) | — | — | — | — |
| ISO metric fine | M56 | 2 mm | 56 mm | 53.835 mm | 54.701 mm | 54 mm (Optimas) | — | — | — | — |
| ISO metric fine | M56 | 4 mm | 56 mm | 51.670 mm | 53.402 mm | 52 mm (Optimas) | — | — | — | — |

## Where the files are

- Mutual Screw & Supply: [Tap and clearance drill chart UNC #1 to 1-1/2 and UNF #0 to 1: fractional and number / letter drills with decimals](https://mutualscrew.com/pages/tap-drill-bit-size-chart) — web — Publisher's page; dimensions are facts
- East Tennessee State University (Hemphill): [Tap drill chart UNC / UNF 0-80 to 1 in-14 with drill designation and decimal](https://faculty.etsu.edu/hemphill/tap_drill.htm) — web — Publisher's page; dimensions are facts
- Engineering ToolBox: [ANSI/ASME B1.1 Unified National threads, UNC and UNF: TPI, major diameter in / mm, tap drill mm, pitch mm, #0 to 4 in](https://www.engineeringtoolbox.com/unified-screw-threads-unc-unf-d_1809.html) — web — Publisher's page; dimensions are facts
- Optimas: [Tapping sizes: ISO metric coarse M1 to M76 (pitch, tapping drill, close / medium / free clearance) and fine pitch (size, pitch, drill)](https://optimas.com/technical-resources/tapping-sizes/) — web — Publisher's page; dimensions are facts
- Engineering ToolBox: [ISO metric thread drill and tap sizes (cites ISO 724): nominal diameter, pitch, clearance fine / medium / coarse, tap drill M1.6 to M30](https://www.engineeringtoolbox.com/iso-metric-thread-drill-tap-size-d_2045.html) — web — Publisher's page; dimensions are facts
- Albany County Fasteners: [Clearance hole chart: inch series close / normal / loose drills (#0 to 1 in) and metric series ISO 273 close H12 / normal H13 / loose H14 (M1.6 to M30)](https://www.albanycountyfasteners.com/media/6b/b8/g0/1764944339/clearance-hole-chart.pdf) — web — Publisher's page; dimensions are facts
- ISO (standards body listing): [ISO 273:1979 Fasteners: clearance holes for bolts and screws (listing; the standard's table was not read)](https://www.iso.org/standard/4183.html) — web — Publisher's page; dimensions are facts

## Questions

**What tap drill for a 1/4-20 thread?**

#7 (0.2010 in, 5.11 mm) per the Mutual Screw and ETSU charts; Engineering ToolBox rounds to 5.35 mm. Clearance: F (0.2570 in) close fit, 17/64 (0.2656 in) normal, 9/32 (0.2812 in) loose (Albany).

**What tap drill and clearance hole for an M5 screw?**

Tap drill 4.2 mm (Optimas and Engineering ToolBox). Clearance 5.3 mm close (H12), 5.5 mm normal (H13), 5.8 mm loose (H14), the same in Albany, Optimas and Engineering ToolBox.

**What is the minor diameter of an M6 x 1 thread?**

4.917 mm basic minor diameter D1 (computed: 6 - 1.0825 x 1) and 5.350 mm pitch diameter (computed); the tap drill is 5 mm.

**What tap drill for #6-32?**

#36 (0.1065 in, 2.71 mm); Engineering ToolBox gives 2.85 mm. Clearance #25 (0.1495 in) normal, #27 (0.1440 in) close, #18 (0.1695 in) loose.

## Fits with

- [Imperial machine screws: #4-40, #6-32, #8-32, 1/4-20](https://xemstudio.com/objects/imperial-machine-screws/)
- [Machine screws, inch (ASME B18.6.3): pan, 82° flat, round, truss, fillister heads #0 to 1/2 — head, slot and recess sizes + envelope models](https://xemstudio.com/objects/machine-screws-inch-asme-b18-6-3/)
- [Socket head cap screws, inch #0 to 1-1/2 (ASME B18.3): head, hex socket, key engagement — full size table + models #0 to 1](https://xemstudio.com/objects/socket-head-cap-screws-inch-full/)
- [Metric machine screws M1.6–M10: pan head ISO 7045 (cross) / ISO 1580 (slotted), cheese head ISO 1207, countersunk ISO 7046-1 — head sizes, recess sizes + models](https://xemstudio.com/objects/machine-screws-metric-pan-cheese-csk/)
- [Socket head cap screws, M2–M8 (ISO 4762 / DIN 912)](https://xemstudio.com/objects/socket-head-cap-screws-metric/)
- [Hex nuts, inch: #4-40 to 3/4-10 (ASME B18.2.2)](https://xemstudio.com/objects/hex-nuts-inch/)
- [Hex nuts, M2–M8 (ISO 4032)](https://xemstudio.com/objects/hex-nuts-metric/)
- [Helical wire thread inserts (Helicoil style, DIN 8140): M3–M16 drill size, tapped hole, insert length 1D–3D](https://xemstudio.com/objects/helical-thread-inserts-din-8140/)
- [Heat-set threaded inserts, inch: #2-56 to 3/8-16 and G1/8 (CNC Kitchen sizes)](https://xemstudio.com/objects/heat-set-inserts-inch/)
- [Hex bolts, inch: 1/4-20 to 3/4-10 (ASME B18.2.1)](https://xemstudio.com/objects/hex-bolts-inch/)
- [Drill size chart: number #1–#80, letter A–Z, fractional 1/64–1 in and metric drills in decimal inches and mm (ASME B94.11M)](https://xemstudio.com/objects/drill-size-index-number-letter-fraction/)
- [NPT pipe thread dimensions (ASME B1.20.1): TPI, E0, E1, L1, L2 and tap drill, NPS 1/8 to 6 + male NPT end STEP/STL](https://xemstudio.com/objects/npt-thread-dimensions-asme-b1-20-1/)