Predrilling is a must when your job requires tapping a hole in metal. Once you determine what size tap is needed, you must know what size hole to pre-drill. Our drill tap chart below will assist you in finding the correct size drill bit for fractional, taper pipe, and metric taps.
Fractional Drill Tap Chart
Fractional / Drill Size Decimal Equivalent Tap Size Fractional / Drill Size Decimal Equivalent Tap Size 80 .0135 3 .2130 1/4″-28 79 .0145 7/32″ .2188 1/64″ .0156 2 .2210 78 .0160 1 .2280 77 .0180 A .2340 76 .0200 15/64″ .2344 75 .0210 B .2380 74 .0225 C .2420 73 .0240 D .2460 72 .0250 1/4″,E .2500 71 .0260 F .2570 5/16″-18 70 .0292 G .2610 69 .0310 17/64″ .2656 68 .0312 H .2660 1/32″ .0320 I .2720 5/16″-24 67 .0330 J .2770 66 .0350 K .2810 65 .0360 9/32″ .2812 64 .0370 L .2900 63 .0380 M .2950 62 .0390 19/64″ .2969 61 .0400 N .3020 60 .0410 5/16″ .3125 3/8″-16 59 .0420 O .3160 58 .0430 P .3230 57 .0465 21/64″ .3281 56 0.465 Q .3320 3/8″-24 3/64″ .0469 0-80 R .3390 55 .0520 11/32″ .3438 54 .0550 S .3480 53 .0595 1-64,72 T .3580 1/16″ .0625 23/64″ .3594 52 .0635 U .3680 7/16″-14 51 .0670 3/8″ .3750 50 .0700 2-56,64 V .3770 49 .0730 W .3860 48 .0760 25/64″ .3906 7/16″-20 5/64″ .0781 X .3970 47 .0785 3-48 Y .4040 46 .0810 13/32″ .4062 45 .0820 3-56 Z .4130 44 .0860 27/64″ .4219 1/2″-13 43 .0890 4-40 7/16″ .4375 42 .0935 4-48 29/64″ .4531 1/2″-20 3/32″ .0938 15/32″ .4688 41 .0960 31/64″ .4844 9/16″-12 40 .0980 1/2″ .5000 39 .0995 33/64″ .5156 9/16″-18 38 .1015 5-40 17/32″ .5312 5/8″-11 37 .1040 5-44 35/64″ .5469 36 .1065 6-32 9/16″ .5625 7/64″ .1094 37/64″ .5781 5/8″-18 35 .1100 19/32″ .5938 34 .1110 39/64″ .6094 33 .1130 6-40 5/8″ .6250 32 .1160 41/64″ .6406 31 .1200 21/32″ .6562 3/4″-10 1/8″ .1250 43/64″ .6719 30 .1285 11/16″ .6875 3/4″-16 29 .1360 8-32,36 45/64″ .7031 28 .1405 23/32″ .7188 9/64″ .1406 47/64″ .7344 27 .1440 3/4″ .7500 26 .1470 49/64” .7656 7/8″-9 25 .1495 10-24 25/32″ .7812 24 .1520 51/64″ .7969 23 .1540 13/16″ .8125 7/8″-14 5/32″ .1562 53/64″ .8281 22 .1570 27/32″ .8438 21 .1590 10-32 55/64″ .8594 20 .1610 7/8″ .8750 1″-8 19 .1660 57/64″ .8906 18 .1695 29/32″ .9062 11/64″ .1719 59/64″ .9219 17 .1730 15/16″ .9375 16 .1770 12-24 61/64″ .9531 15 .1800 31/32″ .9688 14 .1820 12-28 63/64″ .9844 1-1/8″-7 13 .1850 1″ 1.0000 3/16″ .1875 1-3/64″ 1.0469 1-1/8″-12 12 .1890 1-7/64″ 1.1094 1-1/4″-7 11 ..1910 1-1/8″ 1.1250 10 .1935 1-11/64″ 1.1719 1-1/4″-12 9 .1960 1-7/32″ 1.2188 1-3/8″-6 8 .1990 1-1/4″ 1.2500 7 .2010 1/4″-20 1-19/64″ 1.2969 1-3/8″-12 13/64″ .2031 1-11/32″ 1.3438 1-1/2″-6 6 .2040 1-3/8″ 1.3750 5 .2055 1-27/64″ 1.4219 1-1/2″-12 4 .2090 1-1/2″ 1.5000
Pipe Thread Drill Tap Chart
Taper Pipe Thread Size Drill Size (in) 1/8″-27 11/32″ 1/4″-18 7/16″ 3/8″-18 37/64″ 1/2″-14 23/32″ 3/4″-14 59/64″ 1″-11-1/2 1-5/32″ 1-1/4″-11-1/2 1-1/2″ 1-1/2″-11-1/2 1-3/4″ 2″-11-1/2 2-7/32″ 2-1/2″-8 2-21/32″ 3″-8 3-1/4″ 3-1/2″-8 3-3/4″ 4″-8 4-1/4″
Metric Thread Drill Tap Chart
Metric Tap Size Drill Size (mm) Decimal Equivalent (in) M1.6X0.35 1.25 .0492 M1.8X0.35 1.45 .0571 M2X0.4 1.60 .0630 M2.2X0.45 1.75 .0689 M2.5X0.45 2.05 .0807 M3X0.5 2.50 .0984 M3.5X0.6 2.90 .1142 M4X0.7 3.30 .1299 M4.5X0.75 3.70 .1457 M5X0.8 4.20 .1654 M6X1 5.00 .1968 M7X1 6.00 .2362 M8X1.25 6.70 .2638 M8X1.25 7.00 .2756 M10X1.5 8.50 .3346 M10X1.25 8.70 .3425 M12X1.75 10.20 .4016 M12.1.25 10.80 .4252 M14X2 12.00 .4724 M14X1.5 12.50 .4921 M16X2 14.00 .5512 M16X1.5 14.50 .5709 M18X2.5 15.50 .6102 M18X1.5 16.50 .6496 M20X2.5 17.50 .6890 M20X1.5 18.50 .7283 M22X2.5 19.50 .7677 M22X1.5 20.50 .8071 M24X3 21.00 .8268 M24X2 22.00 .8661 M27X3 24.00 .9449 M27X2 25.00 .9843 M30X3.5 26.50 1.0433 M30X2 28.00 1.1024 M33X3.5 29.50 1.1614 M33X2 31.00 1.2205 M36X4 32.00 1.2598 M36X3 33.00 1.2992 M39X4 35.00 1.3780 M39X3 36.00 1.4173
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