| Bolt Size | Standard | Recommended CS Dia. | Head Range |
|---|---|---|---|
| #0 (0.060") | 82° Imp | 130.0 thou3.30 mm |
110-130 thou2.80-3.30 mm |
| #1 (0.073") | 82° Imp | 160.0 thou4.06 mm |
140-160 thou3.55-4.06 mm |
| #2 (0.086") | 82° Imp | 190.0 thou4.83 mm |
162-190 thou4.11-4.83 mm |
| #4 (0.112") | 82° Imp | 225.0 thou5.71 mm |
207-225 thou5.25-5.72 mm |
| #6 (0.138") | 82° Imp | 279.0 thou7.09 mm |
255-279 thou6.48-7.10 mm |
| #8 (0.164") | 82° Imp | 332.0 thou8.43 mm |
304-332 thou7.72-8.45 mm |
| #10 (0.190") | 82° Imp | 385.0 thou9.78 mm |
352-385 thou8.94-9.80 mm |
| 1/4" (0.250") | 82° Imp | 507.0 thou12.88 mm |
463-507 thou11.76-12.90 mm |
| 5/16" (0.312") | 82° Imp | 635.0 thou16.13 mm |
581-635 thou14.75-16.15 mm |
| 3/8" (0.375") | 82° Imp | 762.0 thou19.35 mm |
697-762 thou17.70-19.40 mm |
| 1/2" (0.500") | 82° Imp | 1017.0 thou25.83 mm |
931-1017 thou23.65-25.85 mm |
| 5/8" (0.625") | 82° Imp | 1250.0 thou31.75 mm |
1145-1250 thou29.10-31.75 mm |
| 3/4" (0.750") | 82° Imp | 1500.0 thou38.10 mm |
1385-1500 thou35.20-38.10 mm |
| M2 | 90° Metric | 173.2 thou4.40 mm |
149-173 thou3.80-4.40 mm |
| M2.5 | 90° Metric | 216.5 thou5.50 mm |
185-216 thou4.70-5.50 mm |
| M3 | 90° Metric | 248.0 thou6.30 mm |
216-248 thou5.50-6.30 mm |
| M4 | 90° Metric | 330.7 thou8.40 mm |
295-331 thou7.50-8.40 mm |
| M5 | 90° Metric | 393.7 thou10.00 mm |
362-394 thou9.20-10.00 mm |
| M6 | 90° Metric | 496.1 thou12.60 mm |
433-496 thou11.00-12.60 mm |
| M8 | 90° Metric | 681.1 thou17.30 mm |
590-681 thou15.00-17.30 mm |
| M10 | 90° Metric | 826.8 thou21.00 mm |
720-827 thou18.30-21.00 mm |
| M12 | 90° Metric | 1023.6 thou26.00 mm |
866-1024 thou22.00-26.00 mm |
| M16 | 90° Metric | 1259.8 thou32.00 mm |
1142-1260 thou29.00-32.00 mm |
| M20 | 90° Metric | 1574.8 thou40.00 mm |
1417-1575 thou36.00-40.00 mm |
Countersink Bolt Size Chart & Specifications
May 2, 2026
Full Size Range (Thou & Metric)