Reference Only. See terms of use.
See ASME B18.2.8-1999 – ” Clearance holes for bolts, screws and studs” Calculator.
Tapping & Clearance Hole Information
Machine Screw Size | Number of Threads Per Inch | Minor Dia. | Tap Drills | Clearance Hole Drills | |||||||
Aluminum, Brass & Plastics75% Thread | Stainless Steel, Steels & Iron50% Thread | All Materials | |||||||||
Close Fit | Free Fit | ||||||||||
No. or Dia. | Major Dia. | Drill Size | Decimal Equiv. | Drill Size | Decimal Equiv. | Drill Size | Decimal Equiv. | Drill Size | Decimal Equiv. | ||
0 | .0600 | 80 | .0447 | 3/64 | .0469 | 55 | .0520 | 52 | .0635 | 50 | .0700 |
1 | .0730 | 64 | .0538 | 53 | .0595 | 1/16 | .0625 | 48 | .0760 | 46 | .0810 |
72 | .0560 | 53 | .0595 | 52 | .0635 | ||||||
2 | .0860 | 56 | .0641 | 50 | .0700 | 49 | .0730 | 43 | .0890 | 41 | .0960 |
64 | .0668 | 50 | .0700 | 48 | .0760 | ||||||
3 | .0990 | 48 | .0734 | 47 | .0785 | 44 | .0860 | 37 | .1040 | 35 | .1100 |
56 | .0771 | 45 | .0820 | 43 | .0890 | ||||||
4 | .1120 | 40 | .0813 | 43 | .0890 | 41 | .0960 | 32 | .1160 | 30 | .1285 |
48 | .0864 | 42 | .0935 | 40 | .0980 | ||||||
5 | .1250 | 40 | .0943 | 38 | .1015 | 7/64 | .1094 | 30 | .1285 | 29 | .1360 |
44 | .0971 | 37 | .1040 | 35 | .1100 | ||||||
6 | .1380 | 32 | .0997 | 36 | .1065 | 32 | .1160 | 27 | .1440 | 25 | .1495 |
Machine Screw Size | Number of Threads Per Inch | Minor Dia. | Tap Drills | Clearance Hole Drills | |||||||
Aluminum, Brass & Plastics75% Thread | Stainless Steel, Steels & Iron50% Thread | All Materials | |||||||||
Close Fit | Free Fit | ||||||||||
No. or Dia. | Major Dia. | Drill Size | Decimal Equiv. | Drill Size | Decimal Equiv. | Drill Size | Decimal Equiv. | Drill Size | Decimal Equiv. | ||
8 | .1640 | 32 | .1257 | 29 | .1360 | 27 | .1440 | 18 | .1695 | 16 | .1770 |
36 | .1299 | 29 | .1360 | 26 | .1470 | ||||||
10 | .1900 | 24 | .1389 | 25 | .1495 | 20 | .1610 | 9 | .1960 | 7 | .2010 |
32 | .1517 | 21 | .1590 | 18 | .1695 | ||||||
12 | .2160 | 24 | .1649 | 16 | .1770 | 12 | .1890 | 2 | .2210 | 1 | .2280 |
28 | .1722 | 14 | .1820 | 10 | .1935 | ||||||
32 | .1777 | 13 | .1850 | 9 | .1960 | ||||||
1/4 | .2500 | 20 | .1887 | 7 | .2010 | 7/32 | .2188 | F | .2570 | H | .2660 |
28 | .2062 | 3 | .2130 | 1 | .2280 | ||||||
32 | .2117 | 7/32 | .2188 | 1 | .2280 | ||||||
5/16 | .3125 | 18 | .2443 | F | .2570 | J | .2770 | P | .3230 | Q | .3320 |
24 | .2614 | I | .2720 | 9/32 | .2812 | ||||||
32 | .2742 | 9/32 | .2812 | L | .2900 | ||||||
3/8 | .3750 | 16 | .2983 | 5/16 | .3125 | Q | .3320 | W | .3860 | X | .3970 |
24 | .3239 | Q | .3320 | S | .3480 | ||||||
32 | .3367 | 11/32 | .3438 | T | .3580 |
Machine Screw Size | Number of Threads Per Inch | Minor Dia. | Tap Drills | Clearance Hole Drills | |||||||
Aluminum, Brass & Plastics75% Thread | Stainless Steel, Steels & Iron50% Thread | All Materials | |||||||||
Close Fit | Free Fit | ||||||||||
No. or Dia. | Major Dia. | Drill Size | Decimal Equiv. | Drill Size | Decimal Equiv. | Drill Size | Decimal Equiv. | Drill Size | Decimal Equiv. | ||
7/16 |
.4375 |
14 | .3499 | U | .3680 | 25/64 | .3906 |
29/64 |
.4531 |
15/32 |
.4687 |
20 | .3762 | 25/64 | .3906 | 13/32 | .4062 | ||||||
28 | .3937 | Y | .4040 | Z | .4130 | ||||||
1/2 | .5000 | 13 | .4056 | 27/64 | .4219 | 29/64 | .4531 | 33/64 | .5156 | 17/32 | .5312 |
20 | .4387 | 29/64 | .4531 | 15/32 | .4688 | ||||||
28 | .4562 | 15/32 | .4688 | 15/32 | .4688 | ||||||
9/16 | .5625 | 12 | .4603 | 31/64 | .4844 | 33/64 | .5156 | 37/64 | .5781 | 19/32 | .5938 |
18 | .4943 | 33/64 | .5156 | 17/32 | .5312 | ||||||
24 | .5114 | 33/64 | .5156 | 17/32 | .5312 | ||||||
5/8 | .6250 | 11 | .5135 | 17/32 | .5312 | 9/16 | .5625 | 41/64 | .6406 | 21/32 | .6562 |
18 | .5568 | 37/64 | .5781 | 19/32 | .5938 | ||||||
24 | .5739 | 37/64 | .5781 | 19/32 | .5938 | ||||||
11/16 | .6875 | 24 | .6364 | 41/64 | .6406 | 21/32 | .6562 | 45/64 | .7031 | 23/32 | .6562 |
Machine Screw Size | Number of Threads Per Inch | Minor Dia. | Tap Drills | Clearance Hole Drills | |||||||
Aluminum, Brass & Plastics75% Thread | Stainless Steel, Steels & Iron50% Thread | All Materials | |||||||||
Close Fit | Free Fit | ||||||||||
No. or Dia. | Major Dia. | Drill Size | Decimal Equiv. | Drill Size | Decimal Equiv. | Drill Size | Decimal Equiv. | Drill Size | Decimal Equiv. | ||
3/4 |
.7500 |
10 | .6273 | 21/32 | .6562 | 11/16 | .6875 |
49/64 |
.7656 |
25/32 |
.7812 |
16 | .6733 | 11/16 | .6875 | 45/64 | .7031 | ||||||
20 | .6887 | 45/64 | .7031 | 23/32 | .7188 | ||||||
13/16 | .8125 | 20 | .7512 | 49/64 | .7656 | 25/32 | .7812 | 53/64 | .8281 | 27/32 | .8438 |
7/8 | .8750 | 9 | .7387 | 49/64 | .7656 | 51/64 | .7969 | 57/64 | .8906 | 29/32 | .9062 |
14 | .7874 | 13/16 | .8125 | 53/64 | .8281 | ||||||
20 | .8137 | 53/64 | .8281 | 27/32 | .8438 | ||||||
15/16 | .9375 | 20 | .8762 | 57/64 | .8906 | 29/32 | .9062 | 61/64 | .9531 | 31/32 | .9688 |
1 | 1.000 | 8 | .8466 | 7/8 | .8750 | 59/64 | .9219 | 1-1/64 | 1.0156 | 1-1/32 | 1.0313 |
12 | .8978 | 15/16 | .9375 | 61/64 | .9531 | ||||||
20 | .9387 | 61/64 | .9531 | 31/32 | .9688 | ||||||
1-1/16 | 1.0625 | 18 | .9943 | 1.000 | 1.000 | 1-1/64 | 1.0156 | 1-5/64 | 1.0781 | 1-3/32 | 1.0938 |
1-1/8 | 1.1250 | 7 | .9497 | 63/64 | .9844 | 1-1/32 | 1.0313 | 1-9/64 | 1.1406 | 1-5/32 | 1.1562 |
12 | 1.0228 | 1-3/64 | 1.0469 | 1-5/64 | 1.0781 | ||||||
18 | 1.0568 | 1-1/16 | 1.0625 | 1-5/64 | 1.0781 | ||||||
1-3/16 | 1.1875 | 18 | 1.1193 | 1-1/8 | 1.1250 | 1-9/64 | 1.1406 | 1-13/64 | 1.2031 | 1-7/32 | 1.2188 |
Machine Screw Size | Number of Threads Per Inch | Minor Dia. | Tap Drills | Clearance Hole Drills | |||||||
Aluminum, Brass & Plastics75% Thread | Stainless Steel, Steels & Iron50% Thread | All Materials | |||||||||
Close Fit | Free Fit | ||||||||||
No. or Dia. | Major Dia. | Drill Size | Decimal Equiv. | Drill Size | Decimal Equiv. | Drill Size | Decimal Equiv. | Drill Size | Decimal Equiv. | ||
1-1/4 |
1.2500 |
7 | 1.0747 | 1-7/64 | 1.1094 | 1-5/32 | 1.1562 |
1-17/64 |
1.2656 |
1-9/32 |
1.2812 |
12 | 1.1478 | 1-11/64 | 1.1719 | 1-13/64 | 1.2031 | ||||||
18 | 1.1818 | 1-3/16 | 1.1875 | 1-13/64 | 1.2031 | ||||||
1-5/16 | 1.3125 | 18 | 1.2443 | 1-1/4 | 1.2500 | 1-17/64 | 1.2656 | 1-21/64 | 1.3281 | 1-11/32 | 1.3438 |
1-3/8 | 1.3750 | 6 | 1.1705 | 1-7/32 | 1.2187 | 1-17/64 | 1.2656 | 1-25/64 | 1.3906 | 1-13/32 | 1.4062 |
12 | 1.2728 | 1-19/64 | 1.2969 | 1-21/64 | 1.3281 | ||||||
18 | 1.3068 | 1-5/16 | 1.3125 | 1-21/64 | 1.3281 | ||||||
1-7/16 | 1.4375 | 18 | 1.3693 | 1-3/8 | 1.3750 | 1-25/64 | 1.3906 | 1-29/64 | 1.4531 | 1-15/32 | 1.4688 |
1-1/2 | 1.500 | 6 | 1.2955 | 1-11/32 | 1.3437 | 1-25/64 | 1.3906 | 1-33/64 | 1.5156 | 1-17/32 | 1.5312 |
12 | 1.3978 | 1-27/64 | 1.4219 | 1-7/16 | 1.4375 | ||||||
18 | 1.4318 | 1-7/16 | 1.4375 | 1-29/64 | 1.4531 | ||||||
1-9/16 | 1.5625 | 18 | 1.4943 | 1-12 | 1.500 | 1-33/64 | 1.5156 | 1-37/64 | 1.5781 | 1-19/32 | 1.5938 |
1-5/8 | 1.625 | 18 | 1.5568 | 1-9/16 | 1.5625 | 1-37/64 | 1.5781 | 1-41/64 | 1.6406 | 1-21/32 | 1.6562 |
1-11/16 | 1.6875 | 18 | 1.6193 | 1-5/8 | 1.6250 | 1-41/64 | 1.6406 | 1-45/64 | 1.7031 | 1-23/32 | 1.7188 |
1-3/4 | 1.750 | 5 | 1.5046 | 1-9/16 | 1.5625 | 1-5/8 | 1.6250 | 1-49/64 | 1.7659 | 1-25/32 | 1.7812 |
Originally posted by http://www.stanford.edu/~jwodin/holes.html
Is there any different size of clearance hole used in different materials is that so can you suggest where we can take the reference