Bolt size & stress-area chart
Metric sizes M2–M100 with coarse pitch, tensile stress area and the nearest imperial (UNC) equivalent. Stress area is what our tensile-load calculator uses.
| Metric size | Coarse pitch (mm) | Stress area (mm²) | Imperial (UNC) | UNC TPI | Stress area (in²) |
|---|---|---|---|---|---|
| M2 | 0.4 | 2.07 | #2 | — | 0.0032 |
| M2.5 | 0.45 | 3.39 | #3 | — | 0.0053 |
| M3 | 0.5 | 5.03 | #6 | 32 | 0.0078 |
| M4 | 0.7 | 8.78 | #8 | 32 | 0.0136 |
| M5 | 0.8 | 14.2 | #10 | 24 | 0.022 |
| M6 | 1 | 20.1 | 1/4" | 20 | 0.0312 |
| M8 | 1.25 | 36.6 | 5/16" | 18 | 0.0567 |
| M10 | 1.5 | 58 | 3/8" | 16 | 0.0899 |
| M12 | 1.75 | 84.3 | 1/2" | 13 | 0.1307 |
| M14 | 2 | 115 | 9/16" | 12 | 0.1783 |
| M16 | 2 | 157 | 5/8" | 11 | 0.2434 |
| M18 | 2.5 | 192 | 11/16" | — | 0.2976 |
| M20 | 2.5 | 245 | 3/4" | 10 | 0.3798 |
| M22 | 2.5 | 303 | 7/8" | 9 | 0.4697 |
| M24 | 3 | 353 | 1" | 8 | 0.5472 |
| M27 | 3 | 459 | 1-1/16" | 7 | 0.7115 |
| M30 | 3.5 | 561 | 1-3/16" | 7 | 0.8696 |
| M33 | 3.5 | 694 | 1-5/16" | 6 | 1.0757 |
| M36 | 4 | 817 | 1-7/16" | 6 | 1.2664 |
| M39 | 4 | 976 | 1-9/16" | — | 1.5128 |
| M42 | 4.5 | 1120 | 1-5/8" | — | 1.736 |
| M45 | 4.5 | 1300 | 1-3/4" | — | 2.0152 |
| M48 | 5 | 1470 | 1-7/8" | — | 2.2785 |
| M52 | 5 | 1760 | 2" | — | 2.728 |
| M56 | 5.5 | 2030 | 2-1/4" | — | 3.1465 |
| M60 | 5.5 | 2360 | 2-3/8" | — | 3.6581 |
| M64 | 6 | 2680 | 2-1/2" | — | 4.1541 |
| M68 | 6 | 3060 | 2-3/4" | — | 4.743 |
| M72 | 6 | 3460 | 2-7/8" | — | 5.363 |
| M76 | 6 | 3890 | 3" | — | 6.0295 |
| M80 | 6 | 4340 | 3-1/8" | — | 6.727 |
| M90 | 6 | 5590 | 3-1/2" | — | 8.6642 |
| M100 | 6 | 6990 | 4" | — | 10.835 |
Coarse thread (metric) / UNC (imperial). Tensile stress areas per ISO 898-1. Imperial equivalents are the nearest standard size, not exact conversions.