Clearance Hole Quick Reference
Printable shop wall chart: Clearance Hole Quick Reference. Free letter-size PDF to print and post at the counter; 25 x 36 inch poster version available.
| Bolt | Close | Normal | Loose |
|---|---|---|---|
| 1/4 | 0.266 | 0.281 | 0.344 |
| 5/16 | 0.328 | 0.344 | 0.406 |
| 3/8 | 0.391 | 0.406 | 0.469 |
| 7/16 | 0.453 | 0.469 | 0.531 |
| 1/2 | 0.531 | 0.562 | 0.656 |
| 5/8 | 0.656 | 0.688 | 0.812 |
| 3/4 | 0.781 | 0.812 | 0.938 |
| 1 | 1.031 | 1.062 | 1.250 |
Metric (ISO 273), mm
| Bolt | Fine | Medium | Coarse |
|---|---|---|---|
| M4 | 4.3 | 4.5 | 4.8 |
| M5 | 5.3 | 5.5 | 5.8 |
| M6 | 6.4 | 6.6 | 7.0 |
| M8 | 8.4 | 9.0 | 10.0 |
| M10 | 10.5 | 11.0 | 12.0 |
| M12 | 13.0 | 13.5 | 14.5 |
| M16 | 17.0 | 17.5 | 18.5 |
| M20 | 21.0 | 22.0 | 24.0 |
| M24 | 25.0 | 26.0 | 28.0 |
ISO 273 fine / medium / coarse is not the same scale as ASME B18.2.8 close / normal / loose. Structural steel uses AISC standard holes: bolt diameter + 1/16 in below 1 in, + 1/8 in at 1 in and above.
These tables carry the same figures as the printed sheet below.
The printed sheet
25 x 36 inch poster version
For the full-size shop poster, tell us where to send it.
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Text version of this sheet
CLEARANCE HOLE
Through-hole sizes for bolts · close, normal and loose fit
Inch (ASME B18.2.8)
Bolt
Close
Normal
Loose
1/4
0.266
0.281
0.344
5/16
0.328
0.344
0.406
3/8
0.391
0.406
0.469
7/16
0.453
0.469
0.531
1/2
0.531
0.562
0.656
5/8
0.656
0.688
0.812
3/4
0.781
0.812
0.938
1
1.031
1.062
1.250
Metric (ISO 273), mm
Bolt
Fine
Medium
Coarse
M4
4.3
4.5
4.8
M5
5.3
5.5
5.8
M6
6.4
6.6
7.0
M8
8.4
9.0
10.0
M10
10.5
11.0
12.0
M12
13.0
13.5
14.5
M16
17.0
17.5
18.5
M20
21.0
22.0
24.0
M24
25.0
26.0
28.0
ISO 273 fine / medium / coarse is not the same scale as ASME B18.2.8 close / normal / loose. Structural steel uses AISC standard holes: bolt diameter + 1/16 in below 1 in, + 1/8 in at 1 in
and above.
The Fastener App | TheFastenerApp.com
Fastener Guide reference FG-1A337B · thefastenerapp.com/fastener-guide/wall-charts/clearance-hole-quick-reference · © The Fastener App. Reference only — verify the current governing standard, drawing and manufacturer data before specifying or installing.
