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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? · 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

Also called: tap drill size chart, #6-32 tap drill size, 1/4-20 tap drill, 10-32 tap drill size, 8-32 tap drill size, #10-24 tap drill, 3/8-16 tap drill size, 5/16-18 tap drill, m3 tap drill size, m4 tap drill size, m5 tap drill size, m6 tap drill size, m8 tap drill size, m10 tap drill, m3 clearance hole, m4 clearance hole size, m5 clearance hole, m6 clearance hole, #6 clearance hole, #8 clearance hole size, 1

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. Mating features

sizes
201 in table

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.

Thread size reference: UNC / UNF and ISO metric coarse / fine —… size chart

seriessizepitch / TPImajor diameterminor diameter D1 (computed)pitch diameter d2 (computed)tap drilltap drill, second sourceclearance hole: close / normal / loose (Albany; ISO 273 for metric)clearance hole, other source 1clearance hole, other source 2
UNC (coarse)#164 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 mmclose #48 (0.0760); normal #46 (0.0810); loose #43 (0.0890) in#47 (0.0785 in)—
UNC (coarse)#256 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 mmclose #43 (0.0890); normal #41 (0.0960); loose #37 (0.1040) in#42 (0.0935 in)—
UNC (coarse)#348 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 mmclose #38 (0.1015); normal #36 (0.1065); loose #32 (0.1160) in#37 (0.1040 in)—
UNC (coarse)#440 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 mmclose #32 (0.1160); normal #30 (0.1285); loose #27 (0.1440) in#31 (0.1200 in)—
UNC (coarse)#540 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 mmclose #30 (0.1285); normal #29 (0.1360); loose #23 (0.1540) in#29 (0.1360 in)—
UNC (coarse)#632 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 mmclose #27 (0.1440); normal #25 (0.1495); loose #18 (0.1695) in#25 (0.1495 in)—
UNC (coarse)#832 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 mmclose #18 (0.1695); normal #15 (0.1800); loose #10 (0.1935) in#16 (0.1770 in)—
UNC (coarse)#1024 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 mmclose #9 (0.1960); normal #5 (0.2055); loose #2 (0.2210) in#9 (0.1960 in)—
UNC (coarse)#1224 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 mmclose #2 (0.2210); normal 7/32 (0.2344); loose 1/4 (0.2500) in#2 (0.2210 in)—
UNC (coarse)1/420 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 mmclose F (0.2570); normal 17/64 (0.2656); loose 9/32 (0.2812) inF (0.2570 in)—
UNC (coarse)5/1618 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 mmclose 21/64 (0.3281); normal 11/32 (0.3438); loose 3/8 (0.3750) inQ (0.3320 in)—
UNC (coarse)3/816 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 mmclose 25/64 (0.3906); normal 13/32 (0.4062); loose 7/16 (0.4375) inW (0.3860 in)—
UNC (coarse)7/1614 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 mmclose 29/64 (0.4531); normal 15/32 (0.4688); loose 1/2 (0.5000) in29/64 (0.4531 in)—
UNC (coarse)1/213 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 mmclose 33/64 (0.5156); normal 17/32 (0.5312); loose 9/16 (0.5625) in33/64 (0.5156 in)—
UNC (coarse)9/1612 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 mmclose 37/64 (0.5781); normal 19/32 (0.5938); loose 5/8 (0.6250) in37/64 (0.5781 in)—
UNC (coarse)5/811 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 mmclose 41/64 (0.6406); normal 21/32 (0.6562); loose 11/16 (0.6875) in41/64 (0.6406 in)—
UNC (coarse)3/410 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 mmclose 49/64 (0.7656); normal 25/32 (0.7812); loose 13/16 (0.8125) in49/64 (0.7656 in)—
UNC (coarse)7/89 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 mmclose 57/64 (0.8906); normal 29/32 (0.9062); loose 15/16 (0.9375) in57/64 (0.8906 in)—
UNC (coarse)18 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 mmclose 1-1/64 (1.0156); normal 1-1/32 (1.0312); loose 1-1/16 (1.0625) in1-1/64 (1.0156 in)—
UNC (coarse)1-1/87 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)1-1/47 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)1-3/86 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)1-1/26 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)#080 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 mmclose #52 (0.0635); normal #50 (0.0700); loose #46 (0.0810) in#51 (0.0670 in)—
UNF (fine)#172 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 mmclose #48 (0.0760); normal #46 (0.0810); loose #43 (0.0890) in#47 (0.0785 in)—
UNF (fine)#264 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 mmclose #43 (0.0890); normal #41 (0.0960); loose #37 (0.1040) in#42 (0.0935 in)—
UNF (fine)#356 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 mmclose #38 (0.1015); normal #36 (0.1065); loose #32 (0.1160) in#37 (0.1040 in)—
UNF (fine)#448 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 mmclose #32 (0.1160); normal #30 (0.1285); loose #27 (0.1440) in#31 (0.1200 in)—
UNF (fine)#544 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 mmclose #30 (0.1285); normal #29 (0.1360); loose #23 (0.1540) in#29 (0.1360 in)—
UNF (fine)#640 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 mmclose #27 (0.1440); normal #25 (0.1495); loose #18 (0.1695) in#25 (0.1495 in)—
UNF (fine)#836 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 mmclose #18 (0.1695); normal #15 (0.1800); loose #10 (0.1935) in#16 (0.1770 in)—
UNF (fine)#1032 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 mmclose #9 (0.1960); normal #5 (0.2055); loose #2 (0.2210) in#9 (0.1960 in)—
UNF (fine)#1228 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 mmclose #2 (0.2210); normal 7/32 (0.2344); loose 1/4 (0.2500) in#2 (0.2210 in)—
UNF (fine)1/428 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 mmclose F (0.2570); normal 17/64 (0.2656); loose 9/32 (0.2812) inF (0.2570 in)—
UNF (fine)5/1624 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 mmclose 21/64 (0.3281); normal 11/32 (0.3438); loose 3/8 (0.3750) inQ (0.3320 in)—
UNF (fine)3/824 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 mmclose 25/64 (0.3906); normal 13/32 (0.4062); loose 7/16 (0.4375) inW (0.3860 in)—
UNF (fine)7/1620 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 mmclose 29/64 (0.4531); normal 15/32 (0.4688); loose 1/2 (0.5000) in29/64 (0.4531 in)—
UNF (fine)1/220 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 mmclose 33/64 (0.5156); normal 17/32 (0.5312); loose 9/16 (0.5625) in33/64 (0.5156 in)—
UNF (fine)9/1618 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 mmclose 37/64 (0.5781); normal 19/32 (0.5938); loose 5/8 (0.6250) in37/64 (0.5781 in)—
UNF (fine)5/818 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 mmclose 41/64 (0.6406); normal 21/32 (0.6562); loose 11/16 (0.6875) in41/64 (0.6406 in)—
UNF (fine)3/416 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 mmclose 49/64 (0.7656); normal 25/32 (0.7812); loose 13/16 (0.8125) in49/64 (0.7656 in)—
UNF (fine)7/814 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 mmclose 57/64 (0.8906); normal 29/32 (0.9062); loose 15/16 (0.9375) in57/64 (0.8906 in)—
UNF (fine)112 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 mmclose 1-1/64 (1.0156); normal 1-1/32 (1.0312); loose 1-1/16 (1.0625) in1-1/64 (1.0156 in)—
UNF (fine)1-1/812 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)1-1/412 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)1-3/812 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)1-1/212 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 coarseM10.25 mm1 mm0.729 mm0.838 mm0.75 mm (Optimas)——close — / medium 1.2 / free — mm (Optimas)—
ISO metric coarseM1.10.25 mm1.1 mm0.829 mm0.938 mm0.85 mm (Optimas)————
ISO metric coarseM1.20.25 mm1.2 mm0.929 mm1.038 mm0.95 mm (Optimas)——close — / medium 1.4 / free — mm (Optimas)—
ISO metric coarseM1.40.3 mm1.4 mm1.075 mm1.205 mm1.1 mm (Optimas)——close — / medium 1.6 / free — mm (Optimas)—
ISO metric coarseM1.60.35 mm1.6 mm1.221 mm1.373 mm1.25 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 coarseM1.80.35 mm1.8 mm1.421 mm1.573 mm1.45 mm (Optimas)——close — / medium 2 / free — mm (Optimas)—
ISO metric coarseM20.4 mm2 mm1.567 mm1.740 mm1.6 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 coarseM2.20.45 mm2.2 mm1.713 mm1.908 mm1.75 mm (Optimas)——close — / medium 2.8 / free — mm (Optimas)—
ISO metric coarseM2.50.45 mm2.5 mm2.013 mm2.208 mm2.05 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 coarseM30.5 mm3 mm2.459 mm2.675 mm2.5 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 coarseM3.50.6 mm3.5 mm2.850 mm3.110 mm2.9 mm (Optimas)——close — / medium 3.9 / free — mm (Optimas)—
ISO metric coarseM40.7 mm4 mm3.242 mm3.545 mm3.3 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 coarseM4.50.75 mm4.5 mm3.688 mm4.013 mm3.75 mm (Optimas)————
ISO metric coarseM50.8 mm5 mm4.134 mm4.480 mm4.2 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 coarseM61 mm6 mm4.917 mm5.350 mm5 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 coarseM71 mm7 mm5.917 mm6.350 mm6 mm (Optimas)————
ISO metric coarseM81.25 mm8 mm6.647 mm7.188 mm6.75 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 coarseM91.25 mm9 mm7.647 mm8.188 mm7.75 mm (Optimas)————
ISO metric coarseM101.5 mm10 mm8.376 mm9.026 mm8.5 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 coarseM111.5 mm11 mm9.376 mm10.026 mm9.5 mm (Optimas)————
ISO metric coarseM121.75 mm12 mm10.106 mm10.863 mm10.2 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 coarseM142 mm14 mm11.835 mm12.701 mm12 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 coarseM162 mm16 mm13.835 mm14.701 mm14 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 coarseM182.5 mm18 mm15.294 mm16.376 mm15.5 mm (Optimas)——close 19 / medium 20 / free 21 mm (Optimas)—
ISO metric coarseM202.5 mm20 mm17.294 mm18.376 mm17.5 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 coarseM222.5 mm22 mm19.294 mm20.376 mm19.5 mm (Optimas)——close 23 / medium 24 / free 26 mm (Optimas)—
ISO metric coarseM243 mm24 mm20.752 mm22.051 mm21 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 coarseM273 mm27 mm23.752 mm25.051 mm24 mm (Optimas)——close 28 / medium 30 / free 32 mm (Optimas)—
ISO metric coarseM303.5 mm30 mm26.211 mm27.727 mm26.5 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 coarseM333.5 mm33 mm29.211 mm30.727 mm29.5 mm (Optimas)——close 34 / medium 36 / free 38 mm (Optimas)—
ISO metric coarseM364 mm36 mm31.670 mm33.402 mm32 mm (Optimas)——close 37 / medium 39 / free 42 mm (Optimas)—
ISO metric coarseM394 mm39 mm34.670 mm36.402 mm35 mm (Optimas)——close 40 / medium 42 / free 45 mm (Optimas)—
ISO metric coarseM424.5 mm42 mm37.129 mm39.077 mm37.5 mm (Optimas)——close 43 / medium 45 / free 48 mm (Optimas)—
ISO metric coarseM454.5 mm45 mm40.129 mm42.077 mm40.5 mm (Optimas)——close 46 / medium 48 / free 52 mm (Optimas)—
ISO metric coarseM485 mm48 mm42.587 mm44.752 mm43 mm (Optimas)——close 50 / medium 52 / free 56 mm (Optimas)—
ISO metric coarseM525 mm52 mm46.587 mm48.752 mm47 mm (Optimas)——close 54 / medium 56 / free 62 mm (Optimas)—
ISO metric coarseM565.5 mm56 mm50.046 mm52.428 mm50.5 mm (Optimas)————
ISO metric coarseM605.5 mm60 mm54.046 mm56.428 mm54.5 mm (Optimas)————
ISO metric coarseM646 mm64 mm57.505 mm60.103 mm58 mm (Optimas)————
ISO metric fineM20.25 mm2 mm1.729 mm1.838 mm1.75 mm (Optimas)————
ISO metric fineM2.20.25 mm2.2 mm1.929 mm2.038 mm1.95 mm (Optimas)————
ISO metric fineM2.30.25 mm2.3 mm2.029 mm2.138 mm2.05 mm (Optimas)————
ISO metric fineM2.50.35 mm2.5 mm2.121 mm2.273 mm2.15 mm (Optimas)————
ISO metric fineM2.60.35 mm2.6 mm2.221 mm2.373 mm2.25 mm (Optimas)————
ISO metric fineM30.35 mm3 mm2.621 mm2.773 mm2.65 mm (Optimas)————
ISO metric fineM3.50.35 mm3.5 mm3.121 mm3.273 mm3.15 mm (Optimas)————
ISO metric fineM40.35 mm4 mm3.621 mm3.773 mm3.65 mm (Optimas)————
ISO metric fineM40.5 mm4 mm3.459 mm3.675 mm3.5 mm (Optimas)————
ISO metric fineM50.35 mm5 mm4.621 mm4.773 mm4.65 mm (Optimas)————
ISO metric fineM50.5 mm5 mm4.459 mm4.675 mm4.5 mm (Optimas)————
ISO metric fineM50.75 mm5 mm4.188 mm4.513 mm4.25 mm (Optimas)————
ISO metric fineM5.50.5 mm5.5 mm4.959 mm5.175 mm5 mm (Optimas)————
ISO metric fineM60.5 mm6 mm5.459 mm5.675 mm5.5 mm (Optimas)————
ISO metric fineM60.75 mm6 mm5.188 mm5.513 mm5.25 mm (Optimas)————
ISO metric fineM70.75 mm7 mm6.188 mm6.513 mm6.25 mm (Optimas)————
ISO metric fineM80.5 mm8 mm7.459 mm7.675 mm7.5 mm (Optimas)————
ISO metric fineM80.75 mm8 mm7.188 mm7.513 mm7.25 mm (Optimas)————
ISO metric fineM81 mm8 mm6.917 mm7.350 mm7 mm (Optimas)————
ISO metric fineM90.75 mm9 mm8.188 mm8.513 mm8.25 mm (Optimas)————
ISO metric fineM91 mm9 mm7.917 mm8.350 mm8 mm (Optimas)————
ISO metric fineM100.5 mm10 mm9.459 mm9.675 mm9.5 mm (Optimas)————
ISO metric fineM100.75 mm10 mm9.188 mm9.513 mm9.25 mm (Optimas)————
ISO metric fineM101 mm10 mm8.917 mm9.350 mm9 mm (Optimas)————
ISO metric fineM101.25 mm10 mm8.647 mm9.188 mm8.75 mm (Optimas)————
ISO metric fineM110.75 mm11 mm10.188 mm10.513 mm10.25 mm (Optimas)————
ISO metric fineM111 mm11 mm9.917 mm10.350 mm10 mm (Optimas)————
ISO metric fineM111.25 mm11 mm9.647 mm10.188 mm9.75 mm (Optimas)————
ISO metric fineM120.5 mm12 mm11.459 mm11.675 mm11.5 mm (Optimas)————
ISO metric fineM120.75 mm12 mm11.188 mm11.513 mm11.25 mm (Optimas)————
ISO metric fineM121 mm12 mm10.917 mm11.350 mm11 mm (Optimas)————
ISO metric fineM121.25 mm12 mm10.647 mm11.188 mm10.75 mm (Optimas)————
ISO metric fineM121.5 mm12 mm10.376 mm11.026 mm10.5 mm (Optimas)————
ISO metric fineM141 mm14 mm12.917 mm13.350 mm13 mm (Optimas)————
ISO metric fineM141.25 mm14 mm12.647 mm13.188 mm12.75 mm (Optimas)————
ISO metric fineM141.5 mm14 mm12.376 mm13.026 mm12.5 mm (Optimas)————
ISO metric fineM150.75 mm15 mm14.188 mm14.513 mm14.25 mm (Optimas)————
ISO metric fineM151 mm15 mm13.917 mm14.350 mm14 mm (Optimas)————
ISO metric fineM151.5 mm15 mm13.376 mm14.026 mm13.5 mm (Optimas)————
ISO metric fineM160.5 mm16 mm15.459 mm15.675 mm15.5 mm (Optimas)————
ISO metric fineM160.75 mm16 mm15.188 mm15.513 mm15.25 mm (Optimas)————
ISO metric fineM161 mm16 mm14.917 mm15.350 mm15 mm (Optimas)————
ISO metric fineM161.25 mm16 mm14.647 mm15.188 mm14.75 mm (Optimas)————
ISO metric fineM161.5 mm16 mm14.376 mm15.026 mm14.5 mm (Optimas)————
ISO metric fineM171 mm17 mm15.917 mm16.350 mm16 mm (Optimas)————
ISO metric fineM171.5 mm17 mm15.376 mm16.026 mm15.5 mm (Optimas)————
ISO metric fineM180.75 mm18 mm17.188 mm17.513 mm17.25 mm (Optimas)————
ISO metric fineM181 mm18 mm16.917 mm17.350 mm17 mm (Optimas)————
ISO metric fineM181.25 mm18 mm16.647 mm17.188 mm16.75 mm (Optimas)————
ISO metric fineM181.5 mm18 mm16.376 mm17.026 mm16.5 mm (Optimas)————
ISO metric fineM182 mm18 mm15.835 mm16.701 mm16 mm (Optimas)————
ISO metric fineM191 mm19 mm17.917 mm18.350 mm18 mm (Optimas)————
ISO metric fineM201.5 mm20 mm18.376 mm19.026 mm18.5 mm (Optimas)————
ISO metric fineM202 mm20 mm17.835 mm18.701 mm18 mm (Optimas)————
ISO metric fineM221 mm22 mm20.917 mm21.350 mm21 mm (Optimas)————
ISO metric fineM221.5 mm22 mm20.376 mm21.026 mm20.5 mm (Optimas)————
ISO metric fineM222 mm22 mm19.835 mm20.701 mm20 mm (Optimas)————
ISO metric fineM241 mm24 mm22.917 mm23.350 mm23 mm (Optimas)————
ISO metric fineM241.5 mm24 mm22.376 mm23.026 mm22.5 mm (Optimas)————
ISO metric fineM242 mm24 mm21.835 mm22.701 mm22 mm (Optimas)————
ISO metric fineM251 mm25 mm23.917 mm24.350 mm24 mm (Optimas)————
ISO metric fineM251.5 mm25 mm23.376 mm24.026 mm23.5 mm (Optimas)————
ISO metric fineM252 mm25 mm22.835 mm23.701 mm23 mm (Optimas)————
ISO metric fineM271 mm27 mm25.917 mm26.350 mm26 mm (Optimas)————
ISO metric fineM271.5 mm27 mm25.376 mm26.026 mm25.5 mm (Optimas)————
ISO metric fineM272 mm27 mm24.835 mm25.701 mm25 mm (Optimas)————
ISO metric fineM281 mm28 mm26.917 mm27.350 mm27 mm (Optimas)————
ISO metric fineM281.5 mm28 mm26.376 mm27.026 mm26.5 mm (Optimas)————
ISO metric fineM282 mm28 mm25.835 mm26.701 mm26 mm (Optimas)————
ISO metric fineM301 mm30 mm28.917 mm29.350 mm29 mm (Optimas)————
ISO metric fineM301.5 mm30 mm28.376 mm29.026 mm28.5 mm (Optimas)————
ISO metric fineM302 mm30 mm27.835 mm28.701 mm28 mm (Optimas)————
ISO metric fineM303 mm30 mm26.752 mm28.051 mm27 mm (Optimas)————
ISO metric fineM321 mm32 mm30.917 mm31.350 mm31 mm (Optimas)————
ISO metric fineM321.5 mm32 mm30.376 mm31.026 mm30.5 mm (Optimas)————
ISO metric fineM322 mm32 mm29.835 mm30.701 mm30 mm (Optimas)————
ISO metric fineM331.5 mm33 mm31.376 mm32.026 mm31.5 mm (Optimas)————
ISO metric fineM332 mm33 mm30.835 mm31.701 mm31 mm (Optimas)————
ISO metric fineM333 mm33 mm29.752 mm31.051 mm30 mm (Optimas)————
ISO metric fineM351.5 mm35 mm33.376 mm34.026 mm33.5 mm (Optimas)————
ISO metric fineM352 mm35 mm32.835 mm33.701 mm33 mm (Optimas)————
ISO metric fineM353 mm35 mm31.752 mm33.051 mm32 mm (Optimas)————
ISO metric fineM361 mm36 mm34.917 mm35.350 mm35 mm (Optimas)————
ISO metric fineM361.5 mm36 mm34.376 mm35.026 mm34.4 mm (Optimas)————
ISO metric fineM362 mm36 mm33.835 mm34.701 mm34 mm (Optimas)————
ISO metric fineM363 mm36 mm32.752 mm34.051 mm33 mm (Optimas)————
ISO metric fineM381 mm38 mm36.917 mm37.350 mm37 mm (Optimas)————
ISO metric fineM381.5 mm38 mm36.376 mm37.026 mm36.5 mm (Optimas)————
ISO metric fineM382 mm38 mm35.835 mm36.701 mm36 mm (Optimas)————
ISO metric fineM391.5 mm39 mm37.376 mm38.026 mm37.5 mm (Optimas)————
ISO metric fineM392 mm39 mm36.835 mm37.701 mm37 mm (Optimas)————
ISO metric fineM393 mm39 mm35.752 mm37.051 mm36 mm (Optimas)————
ISO metric fineM401 mm40 mm38.917 mm39.350 mm39 mm (Optimas)————
ISO metric fineM401.5 mm40 mm38.376 mm39.026 mm38.5 mm (Optimas)————
ISO metric fineM403 mm40 mm36.752 mm38.051 mm37 mm (Optimas)————
ISO metric fineM421.5 mm42 mm40.376 mm41.026 mm40.5 mm (Optimas)————
ISO metric fineM422 mm42 mm39.835 mm40.701 mm40 mm (Optimas)————
ISO metric fineM423 mm42 mm38.752 mm40.051 mm39 mm (Optimas)————
ISO metric fineM424 mm42 mm37.670 mm39.402 mm38 mm (Optimas)————
ISO metric fineM451.5 mm45 mm43.376 mm44.026 mm43.5 mm (Optimas)————
ISO metric fineM452 mm45 mm42.835 mm43.701 mm43 mm (Optimas)————
ISO metric fineM453 mm45 mm41.752 mm43.051 mm42 mm (Optimas)————
ISO metric fineM481.5 mm48 mm46.376 mm47.026 mm46.5 mm (Optimas)————
ISO metric fineM482 mm48 mm45.835 mm46.701 mm46 mm (Optimas)————
ISO metric fineM483 mm48 mm44.752 mm46.051 mm45 mm (Optimas)————
ISO metric fineM484 mm48 mm43.670 mm45.402 mm44 mm (Optimas)————
ISO metric fineM501.5 mm50 mm48.376 mm49.026 mm48.5 mm (Optimas)————
ISO metric fineM502 mm50 mm47.835 mm48.701 mm48 mm (Optimas)————
ISO metric fineM503 mm50 mm46.752 mm48.051 mm47 mm (Optimas)————
ISO metric fineM521.5 mm52 mm50.376 mm51.026 mm50.5 mm (Optimas)————
ISO metric fineM522 mm52 mm49.835 mm50.701 mm50 mm (Optimas)————
ISO metric fineM523 mm52 mm48.752 mm50.051 mm49 mm (Optimas)————
ISO metric fineM524 mm52 mm47.670 mm49.402 mm48 mm (Optimas)————
ISO metric fineM562 mm56 mm53.835 mm54.701 mm54 mm (Optimas)————
ISO metric fineM564 mm56 mm51.670 mm53.402 mm52 mm (Optimas)————

Mating features

Drawn at the exact size. Open press, slide, run and socket features by your process's clearance (tolerances by process); leave designed gaps and clamp fits as drawn.

featureexactmates withfitfiles
tapped hole, UNC / UNFtap 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 inscrew of the same thread (plain cylinder at the major diameter in the Xem files)designedall
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 sizeslideall
tapped hole, ISO metric coarsetap 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) mmscrew of the same threaddesignedall
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 sizeslideall

Where the files are

Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.

Mutual Screw & SupplyTap and clearance drill chart UNC #1 to 1-1/2 and UNF #0 to 1: fractional and number / letter drills with decimalswebPublisher'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 decimalwebPublisher's page; dimensions are facts
Engineering ToolBoxANSI/ASME B1.1 Unified National threads, UNC and UNF: TPI, major diameter in / mm, tap drill mm, pitch mm, #0 to 4 inwebPublisher's page; dimensions are facts
OptimasTapping sizes: ISO metric coarse M1 to M76 (pitch, tapping drill, close / medium / free clearance) and fine pitch (size, pitch, drill)webPublisher's page; dimensions are facts
Engineering ToolBoxISO metric thread drill and tap sizes (cites ISO 724): nominal diameter, pitch, clearance fine / medium / coarse, tap drill M1.6 to M30webPublisher's page; dimensions are facts
Albany County FastenersClearance 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)webPublisher'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)webPublisher's page; dimensions are facts

Xem scan

File coming

No downloadable true-size file yet: the published figures do not fix the whole shape, and Xem never guesses a number. A measured scan is planned; request it and it moves up.

Let your AI pull this. Add https://xemstudio.com/mcp to Claude, ChatGPT, Cursor or any MCP client (free, no account, one minute) and it can look up exact sizes, mating fits and free STEP/STL from every chat.
Set it up →

Plain text: sheet.txt · JSON: /api/geometry?object=thread-reference-tap-drills-clearance

Schematic, not to scale.

Fits with

Imperial machine screws: #4-40, #6-32, #8-32, 1/4-20, isometric render of a generated part
Imperial machine screws: #4-40, #6-32, #8-32, 1/4-204 sizes★ 18 files
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, isometric render of a generated part
Machine screws, inch (ASME B18.6.3): pan, 82° flat, round, truss, fillister heads #0 to 1/2 — head, slot and recess sizes + envelope models32.5×25.1×32.5 mm★ 54 files
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, isometric render of a generated part
Socket head cap screws, inch #0 to 1-1/2 (ASME B18.3): head, hex socket, key engagement — full size table + models #0 to 150.8×38.1×76.2 mm★ 18 files
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, isometric render of a generated part
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 + models37.5×20.0×37.5 mm★ 36 files
Socket head cap screws, M2–M8 (ISO 4762 / DIN 912), isometric render of a generated part
Socket head cap screws, M2–M8 (ISO 4762 / DIN 912)7 sizes★ 47 files
Hex nuts, inch: #4-40 to 3/4-10 (ASME B18.2.2), isometric render of a generated part
Hex nuts, inch: #4-40 to 3/4-10 (ASME B18.2.2)12 sizes★ 12 files
Hex nuts, M2–M8 (ISO 4032), isometric render of a generated part
Hex nuts, M2–M8 (ISO 4032)7 sizes★ 7 files
Helical wire thread inserts (Helicoil style, DIN 8140): M3–M16 drill size, tapped hole, insert length 1D–3D12 sizes★ sheet
Heat-set threaded inserts, inch: #2-56 to 3/8-16 and G1/8 (CNC Kitchen sizes), isometric render of a generated part
Heat-set threaded inserts, inch: #2-56 to 3/8-16 and G1/8 (CNC Kitchen sizes)14 sizes★ 14 files
Hex bolts, inch: 1/4-20 to 3/4-10 (ASME B18.2.1), isometric render of a generated part
Hex bolts, inch: 1/4-20 to 3/4-10 (ASME B18.2.1)7 sizes★ 47 files

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.