Find Inch, Metric, and NPT Tap Drill Sizes & Decimal Equivalents with a Drill Tap Chart.
When your job requires tapping a hole in metal predrilling is a must. Once you determine what size tap is needed you will have to know what size of hole to pre-drill for that tap. 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 or Drill Size |
Decimal Equivalent |
Tap Size | Fractional or 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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