Fractional, Number, Letter and Metric Sizes
Recommended Tap Drill Sizes Based on Approximately 75% Thread
Inch Decimal Wire mm Tap sizes to be used with drills as indicated
.0059 97 .15 .0063 96 .16 .0067 95 .17 .0071 94 .18 .0075 93 .19 .0079 92 .20 .0083 91 .21 .0087 90 .22 .0091 89 .23 .0094 .24 .0095 88 .0098 .25 .0100 87 .0102 .26 .0105 86 .0106 .27 .0110 85 .28 .0114 .29 .0115 84 .0118 .30 .0120 83 .0125 82 .0126 .32 .0130 81 .0134 .34 .0135 80 .0138 .35 .0142 .36 .0145 79 .0150 .38 1/64 .0156 .0157 .40 .0160 78 .0165 .42 .0173 .44 .0177 .45 .0180 77 .0181 .46 .0189 .48 .0197 .50 .0200 76 .0210 75 .0217 .55 .0225 74 .0236 .60 .0240 73 .0250 72 .0256 .65 .0260 71 .0276 .70 .0280 70 .0292 69 .0295 .75 .0310 68 1/32 .0312 .0315 .80 .0320 67 .0330 66 .0335 .85 .0350 65 .0354 .90 .0360 64 .0370 63 .0374 .95 .0380 62 .0390 61 .0394 1.00 .0400 60 .0410 59 .0413 1.05 .0420 58 .0430 57 .0433 1.10 .0453 1.15 .0465 56 #0-80 3/64 .0469 1.20 .0472
Inch Decimal Wire mm Tap sizes to be used with drills as indicated
.0492 1.25 .0512 1.30 .0520 55 .0531 1.35 .0550 54 #1-64 .0551 1.40 .0571 1.45 .0591 1.50 .0595 53 #1-72 .0610 1.55 1/16 .0625 .0630 1.60 .0635 52 .0650 1.65 .0669 1.70 .0670 51 #2-56 .0689 1.75 .0700 50 #2-64 .0709 1.80 .0728 1.85 .0730 49 .0748 1.90 .0760 48 #3-48 .0768 1.95 5/64 .0781 .0785 47 .0787 2.00 .0807 2.05 .0810 46 #3-56 .0820 45 .0827 2.10 .0846 2.15 .0860 44 #4-40 .0866 2.20 .0886 2.25 .0890 43 .0906 2.30 .0925 2.35 .0935 42 #4-48 3/32 .0938 .0945 2.40 .0960 41 .0965 2.45 .0980 40 #5-40 .0984 2.50 .0995 39 .1015 38 #5-44 .1024 2.60 .1040 37 .1063 2.70 .1065 36 #6-32 .1083 2.75 7/64 .1094 .1100 35 .1102 2.80 .1110 34 #6-40 .1130 33 .1142 2.90 .1160 32 .1181 3.00 .1200 31 .1220 3.10 1/8 .1250 5/32-32NS .1260 3.20 .1280 3.25 .1285 30 5/32-36NS .1299 3.30 .1339 3.40 .1360 29 #8-32 .1378 3.50 .1405 28 9/64 .1406 .1417 3.60 .1440 27 .1457 3.70 .1470 26 #10-24 .1476 3.75
Inch Decimal Wire mm Tap sizes to be used with drills as indicated
.1495 25
.1496 3.80 .1520 24 .1535 3.90 .1540 23 5/32 .1562 .1570 22 #10-32 .1575 4.00 .1590 21 .1610 20 .1614 4.10 .1654 4.20 .1660 19 .1673 4.25 .1693 4.30 .1695 18 11/64 .1719 .1730 17 .1732 4.40 #12-24 .1770 16 .1772 4.50 7/32-24NS .1800 15 .1811 4.60 #12-28 .1820 14 .1850 13 4.70 .1870 4.75 3/16 .1875 .1890 12 4.80 .1910 11 7/32-32NS .1929 4.90 .1935 10 .1960 9 .1969 5.00 .1990 8 .2008 5.10 .2010 7 13/64 .2031 1/4-20 .2040 6 .2047 5.20 .2055 5 .2067 5.25 .2087 5.30 .2090 4 .2126 5.40 .2130 3 .2165 5.50 1/4-28 7/32 .2188 .2205 5.60 .2210 2 .2244 5.70 .2264 5.75 .2280 1 .2283 5.80 .2323 5.90 .2340 A 15/64 .2344 .2362 6.00 .2380 B .2402 6.10 .2420 C .2441 6.20 .2460 D .2461 6.25 .2480 6.30 1/4 .2500 E .2520 6.40 .2559 6.50 .2570 F .2598 6.60 5/16-18NC .2610 G .2638 6.70 17/64 .2656 .2657 6.75 .2660 H .2677 6.80
Inch Decimal Wire mm Tap sizes to be used with drills as indicated
.2717
6.90 5/16-24NF .2720 I .2756 7.00 .2770 J .2795 7.10 .2810 K 5/16-32NS 9/32 .2812 .2835 7.20 .2854 7.25 .2874 7.30 .2900 L .2913 7.40 .2950 M .2953 7.50 19/64 .2969 .2992 7.60 .3020 N .3031 7.70 .3051 7.75 .3071 7.80 .3110 7.90 3/8-16NC 5/16 .3125 .3150 8.00 .3160 O .3189 8.10 .3228 8.20 .3230 P .3248 8.25 .3268 8.30 21/64 .3281 .3307 8.40 3/8-24NF .3320 Q .3346 8.50 .3386 8.60 1/8-27 Pipe .3390 R .3425 8.70 11/32 .3438 .3445 8.75 .3465 8.80 .3480 S .3504 8.90 .3543 9.00 .3580 T .3583 9.10 23/64 .3594 .3622 9.20 .3642 9.25 .3661 9.30 7/16-14NC .3680 U .3701 9.40 .3740 9.50 3/8 .3750 .3770 V .3780 9.60 .3819 9.70 .3839 9.75 .3858 9.80 7/16-20 .3860 W .3898 9.90 25/64 .3906 .3937 10.00 .3970 X .4040 Y 13/32 .4062 .4130 Z .4134 10.50 1/2-13 27/64 .4219 .4331 11.00 1/4-18 Pipe 7/16 .4375 .4528 11.50 1/2-20 29/64 .4531 15/32 .4688 .4724 12.00 9/16-12 31/64 .4844 .4921 12.50 1/2 .5000 .5118 13.00
Inch Decimal mm Tap sizes to be used with drills as indicated
33/64 .5156 9/16-18 17/32 .5312 5/8-11 .5315 13.5 35/64 .5469 .5512 14.0 9/16 .5625 5/8-18NF .5709 14.5 37/64 .5781 .5906 15.0 3/8-18 Pipe 19/32 .5938 39/64 .6094 .6102 15.5 5/8 .6250 11/16-16NS .6299 16.0 41/64 .6406 .6496 16.5 21/32 .6562 3/4-10NC .6693 17.0 43/64 .6719 11/16 .6875 3/4-16NF .6890 17.5 45/64 .7031 .7087 18.0 23/32 .7188 1/2-14 Pipe .7283 18.5 47/64 .7344 .7480 19.0 3/4 .7500 49/64 .7656 7/8-9NC .7677 19.5 25/32 .7812 .7874 20.0 51/64 .7969 .8071 20.5 13/16 .8125 7/8-14NF .8268 21.0 53/64 .8281 27/32 .8438 .8465 21.5 55/64 .8594 .8661 22.0 7/8 .8750 1-8NC .8858 22.5 57/64 .8906 .9055 23.0 29/32 .9062 59/64 .9219 3/4-14 Pipe .9252 23.5 15/16 .9375 1-14 NF .9449 24.0 61/64 .9531 .9646 24.5 31/32 .9688 .9843 25.0 63/64 .9844 1-1/8-7NC 1 1.0000 1.0039 25.5 1-1/64 1.0156 1.0236 26.0 1-1/32 1.0312 1.0433 26.5 1-3-64 1.0469 1-1/8-12NF 1-1/16 1.0625 1.0630 27.0 1-5/64 1.0781 1.0827 27.5 1-3/32 1.0938 1.1024 28.0 1-7/64 1.1094 1-1/4-7NC 1.1220 28.5 1-1/8 1.1250 1-9/64 1.1406 1.1417 29.0 1-5/32 1.1562 1-11-1/2 Pipe 1.1614 29.5 1-11/64 1.1719 1-1/4-12NF
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