Tap Drill Size Chart
Find the size of drill required for your
tap size.
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Start
Start at 1/16, 3/16, 9/16,
7/8, 1 3/8, Pipe
Thread
go to 3/16
| Size |
Thread |
Root |
Drill Size |
Decimal |
| 1/16 |
64 |
0.0422 |
3/64 |
0.0469 |
| 1/16 |
72 |
0.0445 |
3/64 |
0.0469 |
| 5/64 |
60 |
0.0563 |
1/16 |
0.0625 |
| 5/64 |
72 |
0.0601 |
52 |
0.0635 |
| 3/32 |
48 |
0.0667 |
49 |
0.0730 |
| 3/32 |
50 |
0.0678 |
49 |
0.0730 |
| 7/64 |
48 |
0.0823 |
43 |
0.0890 |
| 1/8 |
32 |
0.0844 |
3/32 |
0.0937 |
| 1/8 |
40 |
0.0925 |
38 |
0.1015 |
| 9/64 |
40 |
0.1081 |
32 |
0.1160 |
| 5/32 |
32 |
0.1157 |
1/8 |
0.1250 |
| 5/32 |
36 |
0.1202 |
30 |
0.1285 |
| 11/64 |
32 |
0.1313 |
9/64 |
0.1406 |
| 3/16 |
24 |
0.1334 |
26 |
0.1470 |
go to 3/8
| Size |
Thread |
Root |
Drill Size |
Decimal |
| 3/16 |
32 |
0.1469 |
22 |
0.1570 |
| 13/64 |
24 |
0.1490 |
20 |
0.1610 |
| 7/32 |
24 |
0.1646 |
16 |
0.1770 |
| 7/32 |
32 |
0.1782 |
12 |
0.1890 |
| 15/64 |
24 |
0.1806 |
10 |
0.1935 |
| 1/4 |
20 |
0.1850 |
7 |
0.2010 |
| 1/4 |
24 |
0.1959 |
4 |
0.2090 |
| 1/4 |
27 |
0.2019 |
3 |
0.2130 |
| 1/4 |
28 |
0.2036 |
3 |
0.2130 |
| 1/4 |
32 |
0.2094 |
7/32 |
0.2187 |
| 5/16 |
18 |
0.2403 |
F |
0.2570 |
| 5/16 |
20 |
0.2476 |
17-64 |
0.2656 |
| 5/16 |
24 |
0.2584 |
I |
0.2720 |
| 5/16 |
27 |
0.2644 |
J |
0.2770 |
| 5/16 |
32 |
0.2719 |
9/32 |
0.2812 |
go to 9/16
| Size |
Thread |
Root |
Drill Size |
Decimal |
| 3/8 |
16 |
0.2938 |
5/16 |
0.3125 |
| 3/8 |
20 |
0.3100 |
21/64 |
0.3281 |
| 3/8 |
24 |
0.3209 |
Q |
0.3320 |
| 3/8 |
27 |
0.3269 |
R |
0.3390 |
| 7/16 |
14 |
0.3447 |
U |
0.3680 |
| 7/16 |
20 |
0.3726 |
25/64 |
0.3906 |
| 7/16 |
24 |
0.3834 |
X |
0.3970 |
| 7/16 |
27 |
0.3894 |
Y |
0.4040 |
| 1/2 |
12 |
0.3918 |
27/64 |
0.4219 |
| 1/2 |
13 |
0.4001 |
27/64 |
0.4219 |
| 1/2 |
20 |
0.4351 |
29/64 |
0.4531 |
| 1/2 |
24 |
0.4459 |
29/64 |
0.4531 |
| 1/2 |
27 |
0.4519 |
15/32 |
0.4687 |
| 9/16 |
12 |
0.4542 |
31/64 |
0.4844 |
| 9/16 |
18 |
0.4903 |
33/64 |
0.5156 |
go to 7/8
| Size |
Thread |
Root |
Drill Size |
Decimal |
| 9/16 |
27 |
0.5144 |
17/32 |
0.5312 |
| 5/8 |
11 |
0.5069 |
17/32 |
0.5312 |
| 5/8 |
12 |
0.5168 |
35/64 |
0.5469 |
| 5/8 |
18 |
0.5528 |
37/64 |
0.5781 |
| 5/8 |
27 |
0.5769 |
19/32 |
0.5937 |
| 11/16 |
11 |
0.5694 |
19/32 |
0.5937 |
| 11/16 |
16 |
0.6063 |
5/8 |
0.6250 |
| 3/4 |
10 |
0.6201 |
21/32 |
0.6562 |
| 3/4 |
12 |
0.6418 |
43/64 |
0.6719 |
| 3/4 |
16 |
0.6688 |
11/16 |
0.6875 |
| 3/4 |
27 |
0.7019 |
23/32 |
0.7187 |
| 13/16 |
10 |
0.6826 |
23/32 |
0.7187 |
| 7/8 |
9 |
0.7307 |
49/64 |
0.7656 |
| 7/8 |
12 |
0.7668 |
51/64 |
0.7969 |
go to 1 3/8
| Size |
Thread |
Root |
Drill Size |
Decimal |
| 7/8 |
14 |
0.7822 |
13/16 |
0.8125 |
| 7/8 |
18 |
0.8028 |
53/64 |
0.8281 |
| 7/8 |
27 |
0.8269 |
27/32 |
0.8437 |
| 15/16 |
9 |
0.7932 |
53/64 |
0.8281 |
| 1 |
8 |
0.8376 |
7/8 |
0.8750 |
| 1 |
12 |
0.8918 |
59/64 |
0.9219 |
| 1 |
14 |
0.9072 |
15/16 |
0.9375 |
| 1 |
27 |
0.9519 |
31/32 |
0.9687 |
| 1 1/8 |
7 |
0.9394 |
63/64 |
0.9844 |
| 1 1/8 |
12 |
1.0168 |
1 3/64 |
1.0469 |
| 1 1/8 |
12 |
1.1418 |
1 11/64 |
1.1719 |
| 1 3/8 |
6 |
1.1585 |
1 7/32 |
1.2187 |
go to Pipe Thread
| Size |
Thread |
Root |
Drill Size |
Decimal |
| 1 3/8 |
12 |
1.2668 |
1 19/64 |
1.2969 |
| 1 1/2 |
6 |
1.2835 |
1 11/32 |
1.3437 |
| 1 1/2 |
12 |
1.3918 |
1 27/64 |
1.4219 |
| 1 5/8 |
5.5 |
1.3888 |
1 29/64 |
1.4531 |
| 1 3/4 |
5 |
1.4902 |
1 9/16 |
1.5625 |
| 1 7/8 |
5 |
1.6152 |
1 11/16 |
1.6875 |
| 2 |
4.5 |
1.7113 |
1 25/32 |
1.7812 |
| 2 1/8 |
4.5 |
1.8363 |
1 29/32 |
1.9062 |
| 2 1/4 |
4.5 |
1.9613 |
21/32 |
2.0312 |
| 2 3/8 |
4 |
2.0502 |
2 1/8 |
2.1250 |
| 2 1/2 |
4 |
2.1752 |
2 1/4 |
2.2500 |
Top
Tap Drill Sizes for Pipe Thread
| Pipe Size |
Drill Size - Briggs |
Drill Size - Whitworth |
| 1/8 |
11/32 |
5/16 |
| 1/4 |
7/16 |
27/64 |
| 3/8 |
19/32 |
9/16 |
| 1/2 |
23/32 |
11/16 |
| 3/4 |
15/16 |
29/32 |
| 1 |
5/32 |
1 1/8 |
| 1 1/4 |
1 1/2 |
1 15/32 |
| 1 1/2 |
1 23/32 |
1 25/32 |
| 2 |
2 3/16 |
2 5/32 |
| 2 1/2 |
2 5/8 |
2 25/32 |
| 3 |
3 1/4 |
3 9/32 |
| 3 1/2 |
3 3/4 |
3 3/4 |
| 4 |
4 1/4 |
4 1/4 |
| 4 1/2 |
4 3/4 |
4 3/4 |
| 5 |
5 5/16 |
5 1/4 |
| 6 |
6 3/8 |
6 1/4 |
Top
Back to NC Programming
Rod Canary | E-mail
First posted: Thu Apr 01 11:12:35 PST 1999
Last revised: Mon Apr 12 11:12:35 PST 1999