Thread size reference: UNC / UNF and ISO metric coarse / fine — major, minor and pitch diameter, tap drill, clearance hole (close, normal, loose) — dimension sheet Source: Xem Studio, https://xemstudio.com/objects/thread-reference-tap-drills-clearance/ (sheet CC BY 4.0) 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 Catalog version: 2026-10-20 Sizes: see table below - 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. 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) — — — — Files elsewhere (not hosted by Xem Studio; license as stated by the publisher): - 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 — web — Publisher's page; dimensions are facts — https://mutualscrew.com/pages/tap-drill-bit-size-chart - East Tennessee State University (Hemphill): Tap drill chart UNC / UNF 0-80 to 1 in-14 with drill designation and decimal — web — Publisher's page; dimensions are facts — https://faculty.etsu.edu/hemphill/tap_drill.htm - 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 — web — Publisher's page; dimensions are facts — https://www.engineeringtoolbox.com/unified-screw-threads-unc-unf-d_1809.html - Optimas: Tapping sizes: ISO metric coarse M1 to M76 (pitch, tapping drill, close / medium / free clearance) and fine pitch (size, pitch, drill) — web — Publisher's page; dimensions are facts — https://optimas.com/technical-resources/tapping-sizes/ - 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 — web — Publisher's page; dimensions are facts — https://www.engineeringtoolbox.com/iso-metric-thread-drill-tap-size-d_2045.html - 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) — web — Publisher's page; dimensions are facts — https://www.albanycountyfasteners.com/media/6b/b8/g0/1764944339/clearance-hole-chart.pdf - ISO (standards body listing): ISO 273:1979 Fasteners: clearance holes for bolts and screws (listing; the standard's table was not read) — web — Publisher's page; dimensions are facts — https://www.iso.org/standard/4183.html No true-size file yet: the published figures do not fix the whole shape; a measured scan is planned. API: https://xemstudio.com/api/geometry?object=thread-reference-tap-drills-clearance