Tap & Drill Chart
UNC - UNIFIED NATIONAL COARSE
Size - Imperial |
Threads Per Inch |
TAPPING DRILL SIZE | |||
Preferred | Alternative | ||||
mm | inch | mm | inch | ||
#1 | 64 | 1.50 | 53 | 1.55 | |
#2 | 56 | 1.85 | 50 | 1.80 | |
#3 | 48 | 2.10 | 47 | 2.05 | 5/64 |
#4 | 40 | 2.35 | 3/32 | 2.30 | 43 |
#5 | 40 | 2.65 | 38 | 2.60 | |
#6 | 32 | 2.85 | 36 | 2.80 | 7/64 |
#8 | 32 | 3.50 | 29 | 3.40 | |
#10 | 24 | 3.90 | 25 | 3.00 | 5/32 |
#12 | 24 | 4.50 | 16 | 4.40 | 11/64 |
1/4 | 20 | 5.20 | 13/64 | 5.10 | 7 |
5/16 | 18 | 6.60 | 17/64 | 6.50 | F |
3/8 | 16 | 8.10 | 5/16 | 8.00 | |
7/16 | 14 | 9.50 | 3/8 | 9.40 | 23/64 |
1/2 | 13 | 11.00 | 27/64 | 10.80 | |
9/16 | 12 | 12.20 | 31/64 | ||
5/8 | 11 | 13.80 | 35/64 | 13.50 | 17/32 |
3/4 | 10 | 21/32 | 16.50 | 41/64 | |
7/8 | 9 | 19.50 | 49/64 | ||
1 | 8 | 7/8 | 22.50 | ||
1-1/8 | 7 | 63/64 | 25.00 | ||
1-1/4 | 7 | 1-7/6 | 28.00 | ||
1-3/8 | 6 | 31.00 | 1-7/32 | 30.75 | 1-13/64 |
1-1/2 | 6 | 1-11/32 | 34.00 | 1-21/64 | |
1-3/4 | 5 | 1-9/16 | 39.50 | ||
2 | 4-1/2 | 1-25/32 | 45.00 |
UNF - UNIFIED NATIONAL FINE
Size - Imperial |
Threads Per Inch |
TAPPING DRILL SIZE | |||
Preferred | Alternative | ||||
mm | inch | mm | inch | ||
#0 | 80 | 1.25 | 3/64 | ||
#1 | 72 | 1.55 | 53 | ||
#2 | 64 | 1.90 | 50 | ||
#3 | 56 | 2.15 | 45 | ||
#4 | 48 | 2.40 | 42 | 3/32 | |
#5 | 44 | 2.70 | 37 | 2.65 | |
#6 | 40 | 2.95 | 33 | 2.90 | |
#8 | 36 | 3.60 | 9/64 | 3.50 | 29 |
#10 | 32 | 4.10 | 21 | 4.00 | 5/32 |
#12 | 28 | 4.70 | 14 | 4.60 | |
1/4 | 28 | 5.50 | 7/32 | 5.40 | 3 |
5/16 | 24 | 6.90 | 17/64 | 6.80 | 1 |
3/8 | 24 | 8.50 | Q | 8.40 | 21/64 |
7/16 | 20 | 10.00 | 25/64 | 9.80 | |
1/2 | 20 | 11.50 | 29/64 | ||
9/16 | 18 | 12.90 | 33/64 | 12.80 | |
5/8 | 18 | 14.50 | 37/64 | ||
3/4 | 16 | 17.50 | 11/16 | ||
7/8 | 14 | 20.40 | 13/16 | 20.50 | |
1 | 12 | 23.25 | 59/64 | 23.50 | |
1 | 14* | 23.50 | 15/16 | ||
1-1/8 | 12 | 26.50 | 1-3/64 | ||
1-1/4 | 12 | 29.50 | 1-11/64 | ||
1-3/8 | 12 | 33.00 | 1-19/64 | ||
1-1/2 | 12 | 36.00 | 1-27/64 |
*1-12 Thread is UNF
standard, however 1-14
is popular demand and
generally stocked in
place of 1-12.
METRIC COARSE
Size - MM |
Pitch |
TAPPING DRILL SIZE | |||
Preferred | Alternative | ||||
mm | inch | mm | inch | ||
1.6 | 0.35 | 1.25 | 3/64 | ||
1.7 | 0.35 | 1.35 | 55 | ||
1.8 | 0.35 | 1.45 | 54 | ||
2 | 0.40 | 1.60 | 1/16 | ||
2.5 | 0.45 | 2.05 | 46 | ||
3 | 0.50 | 2.50 | 40 | ||
3.5 | 0.60 | 2.90 | 33 | ||
4 | 0.70 | 3.30 | 30 | ||
4.5 | 0.75 | 3.70 | 27 | ||
5 | 0.80 | 4.30 | 11/64 | 4.20 | 19 |
6 | 1.00 | 5.10 | 13/64 | 5.00 | 9 |
7 | 1.00 | 6.10 | 6.00 | 15/64 | |
8 | 1.25 | 6.90 | H | 6.80 | 17/64 |
9 | 1.25 | 7.90 | 5/16 | 7.80 | |
10 | 1.50 | 8.60 | 11/32 | 8.50 | Q |
11 | 1.50 | 9.50 | 3/8 | ||
12 | 1.75 | 13/32 | 10.20 | Y | |
14 | 2.00 | 12.20 | 31/64 | 12.00 | 15/32 |
16 | 2.00 | 14.25 | 9/16 | 14.00 | 35/64 |
18 | 2.50 | 15.75 | 15.50 | 39/64 | |
20 | 2.50 | 45/64 | 17.50 | 11/16 | |
22 | 2.50 | 23/32 | 19.50 | 49/64 | |
24 | 3.00 | 21.00 | 53/64 | ||
27 | 3.00 | 24.00 | 61/64 | 15/16 | |
30 | 3.50 | 26.50 | 1-3/64 | ||
33 | 3.50 | 1-11/64 | 1-5/32 | ||
36 | 4.00 | 1-17/64 | 29.50 | 1-1/4 | |
39 | 4.00 | 35.00 | 1-3/8 | 32.00 |
METRIC FINE
Size - MM |
Pitch |
TAPPING DRILL SIZE | |||
Preferred | Alternative | ||||
mm | inch | mm | inch | ||
4 | 0.50 | 3.50 | 29 | 9/64 | |
5 | 0.50 | 4.50 | 16 | ||
6 | 0.75 | 5.25 | 5 | ||
7 | 0.75 | 6.25 | D | 6.20 | 1/4 |
8 | 1.00 | 7.00 | J | 7.10 | 9/32 |
10 | 1.25 | 8.75 | 11/32 | S | |
10 | 1.00 | 9.00 | T | 23/64 | |
12 | 1.50 | 10.50 | 27/64 | Z | |
12 | 1.25 | 27/64 | |||
12 | 1.00 | 11.00 | 7/16 | ||
14 | 1.50 | 12.50 | 31/64 | 1/2 | |
16 | 1.50 | 14.75 | 37/64 | 14.50 | 9/16 |
18 | 2.00 | 16.00 | 5/8 | ||
18 | 1.50 | 16.50 | 21/32 | 16.50 | |
20 | 2.00 | 18.00 | 45/64 | ||
20 | 1.50 | 18.50 | 47/64 | ||
22 | 2.00 | 20.00 | 25/32 | ||
22 | 1.50 | 20.50 | 13/16 | 20.50 | |
24 | 2.00 | 22.00 | 7/8 | ||
24 | 1.50 | 22.50 | 7/8 |
BSW - BRITISH STANDARD WHITWORTH
Size - Imperial |
Threads Per Inch |
TAPPING DRILL SIZE | |||
Preferred | Alternative | ||||
mm | inch | mm | inch | ||
1/16* | 60 | 1.20 | 3/64 | 1.05 | |
3/32* | 48 | 1.90 | 49 | 1.75 | |
1/8 | 40 | 2.55 | 2.50 | 3/32 | |
5/32* | 32 | 3.20 | 1/8 | 2.95 | |
3/16 | 24 | 3.70 | 3.60 | 9/64 | |
7/32* | 24 | 4.50 | 4.30 | 11/64 | |
1/4 | 20 | 5.10 | 5.00 | 3/16 | |
5/16 | 18 | 6.50 | 6.40 | 1/4 | |
3/8 | 16 | 7.90 | 5/16 | 7.80 | 19/64 |
7/16 | 14 | 9.50 | 9.20 | 23/64 | |
1/2 | 12 | 10.50 | 13/32 | ||
9/16 | 12 | 12.00 | 15/32 | ||
5/8 | 11 | 13.50 | 17/32 | 33/64 | |
3/4 | 10 | 16.50 | 41/64 | 16.00 | 5/8 |
7/8 | 9 | 3/4 | 19.00 | 47/64 | |
1 | 8 | 22.00 | 55/64 | 27/32 | |
1-1/8 | 7 | 31/32 | 24.50 | 61/64 | |
1-1/4 | 7 | 28.00 | 1-3/32 | 27.50 | 1-5/64 |
1-1/2 | 6 | 33.50 | 1-5/16 | 33.00 | 1-19/64 |
1-3/4 | 5 | 39.00 | 1-17/32 | 38.50 | 1-33/64 |
2 | 1-1/2 | 44.50 | 1-49/64 | 44.00 | 1-3/4 |
BSF - BRITISH STANDARD FINE
Size - Imperial |
Threads Per Inch |
TAPPING DRILL SIZE | |||
Preferred | Alternative | ||||
mm | inch | mm | inch | ||
3/16 | 32 | 4.00 | 5/32 | 3.90 | |
1/4 | 26 | 5.30 | 5.20 | 13/64 | |
5/16 | 22 | 6.80 | 17/64 | 6.70 | |
3/8 | 20 | 8.30 | 21/64 | 8.20 | 5/16 |
7/16 | 18 | 9.50 | 3/8 | ||
1/2 | 16 | 7/16 | 11.00 | 27/64 | |
9/16 | 16 | 1/2 | 12.50 | 31/64 | |
5/8 | 14 | 14.00 | 35/64 | 13.80 | 17/32 |
3/4 | 12 | 16.50 | 21/32 | ||
7/8 | 11 | 25/32 | 19.50 | 49/64 | |
1 | 10 | 57/64 | 22.50 | 7/8 | |
1-1/4 | 9 | 28.50 | 1-1/8 | 1-7/64 | |
1-1/2 | 8 | 34.50 | 1-23/64 | 1-11/32 | |
1-3/4 | 7 | 40.50 | 1-19/32 | 40.00 | 1-37/64 |
NPT - NATIONAL PIPE TAPER
Size - Imperial |
Threads Per Inch |
TAPPING DRILL SIZE | |||
Preferred | Alternative | ||||
mm | inch | mm | inch | ||
1/16 | 27 | D | 6.30 | 1/4 | |
1/8 | 27 | R | 8.70 | 11/32 | |
1/4 | 18 | 7/16 | 11.10 | ||
3/8 | 18 | 9/16 | 14.50 | 37/64 | |
1/2 | 14 | 23/32 | 18.00 | ||
3/4 | 14 | 59/64 | 23.25 | 15/16 | |
1 | 11-1/2 | 1-5/32 | 29.00 | ||
1-1/4 | 11-1/2 | 1-1/2 | 38.00 | ||
1-1/2 | 11-1/2 | 1-47/64 | 44.00 | ||
2 | 11-1/2 | 2-7/32 | 56.00 | ||
2-1/2 | 8 | 2-5/8 | 67.00 | ||
3 | 8 | 3-1/4 | 82.50 |
DRILL SIZE | DEC EQUIV. | MM | DRILL SIZE | DEC EQUIV. | MM | DRILL SIZE | DEC EQUIV. | MM | DRILL SIZE | DEC EQUIV. | MM | |||
- | .0039 | 0.10 | 45 | .0820 | 2.08 | 4 | .2090 | 5.31 | 15/32 | .4688 | 11.91 | |||
- | .0079 | 0.20 | 44 | .0860 | 2.18 | 3 | .2130 | 5.41 | - | .4724 | 12.00 | |||
- | .0098 | 0.25 | 43 | .0890 | 2.26 | 7/32 | .2188 | 5.56 | 31/64 | .4844 | 12.30 | |||
- | .0118 | 0.30 | 42 | .0935 | 2.37 | 2 | .2210 | 6.61 | 1/2 | .5000 | 12.70 | |||
80 | .0135 | 0.34 | 3/32 | .0938 | 2.38 | 1 | .2280 | 5.79 | - | .5118 | 13.00 | |||
79 | .0145 | 0.37 | 41 | .0960 | 2.44 | A | .2340 | 5.94 | 33/64 | .5156 | 13.10 | |||
1/64 | .0156 | 0.40 | 40 | .0980 | 2.50 | 15/64 | .2344 | 5.95 | 17/32 | .5312 | 13.49 | |||
78 | .0160 | 0.41 | 39 | .0995 | 2.53 | - | .2362 | 6.00 | 35/64 | .5469 | 13.89 | |||
77 | .0181 | 0.46 | 38 | .1015 | 2.58 | B | .2380 | 6.05 | - | .5512 | 14.00 | |||
- | .0197 | 0.50 | 37 | .1040 | 2.64 | C | .2420 | 6.15 | 9/16 | .5625 | 1429 | |||
76 | .0200 | 0.51 | 36 | .1065 | 2.71 | D | .2460 | 6.25 | 37/64 | .5781 | 14.68 | |||
75 | .0210 | 0.53 | 7/64 | .1094 | 2.78 | 1/4 | .2500 | 6.35 | - | .5906 | 15.00 | |||
74 | .0225 | 0.57 | 35 | .1100 | 2.79 | E | .2500 | 6.35 | 19/32 | .5938 | 15.08 | |||
- | .0236 | 0.60 | 34 | .1110 | 2.79 | F | .2570 | 6.53 | 39/64 | .6094 | 15.48 | |||
73 | .0240 | 0.61 | 33 | .1130 | 2.87 | G | .2610 | 6.63 | 5/8 | .6250 | 15.88 | |||
72 | .0250 | 0.64 | 32 | .1160 | 2.95 | 17/64 | .2656 | 6.75 | - | .6299 | 16.00 | |||
71 | .0260 | 0.66 | - | .1181 | 3.00 | H | .2660 | 6.76 | 41/64 | .6406 | 16.27 | |||
- | .0276 | 0.70 | 31 | .1200 | 3.05 | I | .2720 | 6.91 | 21/32 | .6562 | 16.67 | |||
70 | .0280 | 0.71 | 1/8 | .1250 | 3.18 | - | .2756 | 7.00 | - | .6693 | 17.00 | |||
69 | .0292 | 0.74 | 30 | .1285 | 3.26 | J | .2770 | 7.04 | 43/64 | .6719 | 17.07 | |||
- | .0295 | 0.75 | 29 | .1360 | 3.45 | K | .2810 | 7.14 | 11/16 | .6875 | 17.46 | |||
68 | .0310 | 0.79 | 28 | .1405 | 3.57 | 9/32 | .2812 | 7.14 | 45/64 | .7031 | 17.88 | |||
1/32 | .0313 | 0.79 | 9/64 | .1406 | 3.57 | L | .2900 | 7.37 | - | .7087 | 18.00 | |||
- | .0315 | 0.80 | 27 | .1440 | 3.66 | M | .2950 | 7.49 | 23/32 | .7188 | 18.26 | |||
67 | .0320 | 0.81 | 26 | .1470 | 3.73 | 19/64 | .2969 | 7.54 | 47/64 | .7344 | 18.65 | |||
66 | .0330 | 0.84 | 25 | .1495 | 3.80 | N | .3020 | 7.67 | - | .7344 | 18.65 | |||
65 | .0350 | 0.89 | 24 | .1520 | 3.86 | 5/16 | .3125 | 7.94 | 3/4 | .7500 | 19.05 | |||
- | .0354 | 0.90 | 23 | .1540 | 3.91 | - | .3150 | 8.00 | 49/64 | .7656 | 19.45 | |||
64 | .0360 | 0.91 | 5/32 | .1562 | 3.97 | O | .3160 | 8.03 | 25/32 | .7812 | 19.84 | |||
63 | .0370 | 0.94 | 22 | .1570 | 3.99 | P | .3230 | 8.20 | - | .7874 | 20.00 | |||
62 | .0380 | 0.97 | - | .1575 | 4.00 | 21/64 | .3281 | 8.33 | 51/64 | .7969 | 20.24 | |||
61 | .0394 | 0.99 | 21 | .1590 | 4.04 | Q | .2230 | 8.43 | 13/16 | .8125 | 20.64 | |||
- | .0394 | 1.00 | 20 | .1610 | 4.09 | R | .3390 | 8.61 | - | .8268 | 21.00 | |||
60 | .0400 | 1.02 | 19 | .1660 | 4.22 | 11/32 | .3438 | 8.73 | 53/64 | .8281 | 21.03 | |||
59 | .0410 | 1.04 | 18 | .1695 | 4.31 | S | .3480 | 8.84 | 27/32 | .8438 | 21.43 | |||
58 | .0420 | 1.07 | 11/64 | .1719 | 4.37 | - | .3543 | 9.00 | 55/64 | .8594 | 21.84 | |||
57 | .0430 | 1.09 | 17 | .1730 | 4.39 | T | .3580 | 9.09 | - | .8661 | 22.00 | |||
56 | .0465 | 1.18 | 16 | .1770 | 4.50 | 23/64 | .3594 | 9.13 | 7/8 | .8750 | 22.23 | |||
3/64 | .0469 | 1.19 | 15 | .1800 | 4.57 | U | .3680 | 9.35 | 57/64 | .8906 | 22.62 | |||
55 | .0520 | 1.32 | 14 | .1820 | 4.62 | 3/8 | .3750 | 9.35 | - | .9055 | 23.00 | |||
54 | .0550 | 1.40 | 13 | .1850 | 4.70 | V | .3770 | 9.56 | 29/32 | .9062 | 23.02 | |||
53 | .0595 | 1.51 | 3/16 | .1875 | 4.76 | W | .3860 | 9.80 | 59/64 | .9219 | 23.42 | |||
1/16 | .0625 | 1.59 | 12 | .1890 | 4.80 | 25/64 | .3906 | 9.92 | 15/16 | .9375 | 23.81 | |||
52 | .0635 | 1.61 | 11 | .1910 | 4.85 | - | .3937 | 10.00 | - | .9449 | 24.00 | |||
51 | .0670 | 1.70 | 10 | .1935 | 4.91 | X | .3970 | 10.08 | 61/64 | .9531 | 24.21 | |||
50 | .0700 | 1.78 | 9 | .1960 | 4.98 | Y | .4040 | 10.26 | 31/32 | .9688 | 24.61 | |||
49 | .0730 | 1.85 | - | .1968 | 5.00 | 13/32 | .4062 | 10.32 | - | .9842 | 25.00 | |||
48 | .0760 | 1.93 | 8 | .1990 | 5.05 | Z | .4130 | 10.49 | 63/64 | .9844 | 25.00 | |||
5/64 | .0781 | 1.98 | 7 | .2010 | 5.11 | 27/64 | .4219 | 10.72 | 1 | 1.00 | 25.40 | |||
47 | .0785 | 1.99 | 13/64 | .2031 | 5.16 | - | .4331 | 11.00 | ||||||
- | .0787 | 2.00 | 6 | .2040 | 5.18 | 7/16 | .4375 | 11.11 | ||||||
46 | .0810 | 1.06 | 5 | .2055 | 5.22 | 29/64 | .4531 | 11.51 |
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