Tapping sizes and clearance holes
Drill size and clearance hole recommendations.
All dimensions are recommendations only and are shown in mm.
Metric threads
Thread | Drill size for tapping standard metric threads | Drill size for tapping fine metric threads | Clearance hole |
---|---|---|---|
M1 | 0.75 | - | 1.2 |
M1.2 | 0.95 | - | 1.4 |
M1.4 | 1.1 | - | 1.6 |
M1.6 | 1.5 | - | 1.8 |
M1.8 | 1.4 | - | 2 |
M2 | 1.6 | - | 2.4 |
M2.2 | 1.7 | - | 2.8 |
M2.5 | 2 | - | 2.9 |
M3 | 2.5 | - | 3.4 |
M3.5 | 2.9 | - | 3.9 |
M4 | 3.3 | - | 4.5 |
M5 | 4.2 | - | 5.5 |
M6 | 5 | - | 6.6 |
M8 | 6.8 | 7 | 9 |
M10 | 8.5 | 8.8 | 11 |
M12 | 10.2 | 10.8 | 13.5 |
M14 | 12 | 12.5 | 15.5 |
M16 | 14 | 14.5 | 17.5 |
M18 | 15.5 | 16.5 | 20 |
M20 | 17.5 | 18.5 | 22 |
M22 | 19.5 | 20.5 | 24 |
M24 | 21 | 22 | 26 |
M27 | 24 | 25 | 30 |
M30 | 26.5 | 28 | 33 |
Unified threads
Screw Size | Threads per Inch | Tapping Hole | Clearance Hole | ||
---|---|---|---|---|---|
Aluminum, Brass, Plastic | Ferrous Materials | All Materials | |||
Close Fit | Free Fit | ||||
Drill Size | Drill Size | Drill Size | Drill Size | ||
0 | 80 | 3/64 | 55 | 52 | 50 |
1 | 64 | 53 | 1/16 | 48 | 46 |
72 | 53 | 52 | |||
2 | 56 | 50 | 49 | 43 | 41 |
64 | 50 | 48 | |||
3 | 48 | 47 | 44 | 37 | 35 |
56 | 45 | 43 | |||
4 | 40 | 43 | 41 | 32 | 30 |
48 | 42 | 40 | |||
5 | 40 | 38 | 7/64 | 30 | 29 |
44 | 37 | 35 | |||
6 | 32 | 36 | 32 | 27 | 25 |
40 | 33 | 31 | |||
8 | 32 | 29 | 27 | 18 | 16 |
36 | 29 | 26 | |||
10 | 24 | 25 | 20 | 9 | 7 |
32 | 21 | 18 | |||
12 | 24 | 16 | 12 | 2 | 1 |
28 | 14 | 10 | |||
32 | 13 | 9 | |||
1/4 | 20 | 7 | 7/32 | F | H |
28 | 3 | 1 | |||
32 | 7/32 | 1 | |||
5/16 | 18 | F | J | P | Q |
24 | I | 9/32 | |||
32 | 9/32 | L | |||
3/8 | 16 | 5/16 | Q | W | X |
24 | Q | S | |||
32 | 11/32 | T | |||
7/16 | 14 | U | 25/64 | 29/64 | 15/32 |
20 | 25/64 | 13/32 | |||
28 | Y | Z | |||
1/2 | 13 | 27/64 | 29/64 | 33/64 | 17/32 |
20 | 29/64 | 15/32 | |||
28 | 15/32 | 15/32 | |||
9/16 | 12 | 31/64 | 33/64 | 37/64 | 19/32 |
18 | 33/64 | 17/32 | |||
24 | 33/64 | 17/32 | |||
5/8 | 11 | 17/32 | 9/16 | 41/64 | 21/32 |
18 | 37/64 | 19/32 | |||
24 | 37/64 | 19/32 | |||
11/16 | 24 | 41/64 | 21/32 | 45/64 | 23/32 |
3/4 | 10 | 21/32 | 11/16 | 49/64 | 25/32 |
16 | 11/16 | 45/64 | |||
20 | 45/64 | 23/32 | |||
13/16 | 20 | 49/64 | 25/32 | 53/64 | 27/32 |
7/8 | 9 | 49/64 | 51/64 | 57/64 | 29/32 |
14 | 13/16 | 53/64 | |||
20 | 53/64 | 27/32 | |||
15/16 | 20 | 57/64 | 29/32 | 61/64 | 31/32 |
1 | 8 | 7/8 | 59/64 | 1-1/64 | 1-1/32 |
12 | 15/16 | 61/64 | |||
20 | 61/64 | 31/32 | |||
1-1/16 | 18 | 1.000 | 1-1/64 | 1-5/64 | 1-3/32 |
1-1/8 | 7 | 63/64 | 1-1/32 | 1-9/64 | 1-5/32 |
12 | 1-3/64 | 1-5/64 | |||
18 | 1-1/16 | 1-5/64 | |||
1-3/16 | 18 | 1-1/8 | 1-9/64 | 1-13/64 | 1-7/32 |
1-1/4 | 7 | 1-7/64 | 1-5/32 | 1-17/64 | 1-9/32 |
12 | 1-11/64 | 1-13/64 | |||
18 | 1-3/16 | 1-13/64 | |||
1-5/16 | 18 | 1-1/4 | 1-17/64 | 1-21/64 | 1-11/32 |
1-3/8 | 6 | 1-7/32 | 1-17/64 | 1-25/64 | 1-13/32 |
12 | 1-19/64 | 1-21/64 | |||
18 | 1-5/16 | 1-21/64 | |||
1-7/16 | 18 | 1-3/8 | 1-25/64 | 1-29/64 | 1-15/32 |
1-1/2 | 6 | 1-11/32 | 1-25/64 | 1-33/64 | 1-17/32 |
12 | 1-27/64 | 1-7/16 | |||
18 | 1-7/16 | 1-29/64 | |||
1-9/16 | 18 | 1-1/2 | 1-33/64 | 1-37/64 | 1-19/32 |
1-5/8 | 18 | 1-9/16 | 1-37/64 | 1-41/64 | 1-21/32 |
1-11/16 | 18 | 1-5/8 | 1-41/64 | 1-45/64 | 1-23/32 |
1-3/4 | 5 | 1-9/16 | 1-5/8 | 1-49/64 | 1-25/32 |