ISO Metric Coarse Thread · DIN 13-1 / ISO 261
M8 Thread: Pitch, Tap Drill & Dimensions
M8 is an ISO metric coarse thread with a 1.25 mm pitch. The tap drill is 6.75 mm, and the internal minor diameter D1 is 6.647 mm.
| Nominal (major) diameter | 8 mm |
|---|---|
| Pitch | 1.25 mm (coarse) |
| Tap drill (D − P) | 6.75 mm |
| Pitch diameter d2 / D2 | 7.188 mm |
| Minor diameter, external d3 | 6.466 mm |
| Minor diameter, internal D1 | 6.647 mm |
| Thread depth, external h3 | 0.767 mm |
| Flank angle | 60° |
| Clearance hole (fine / medium / coarse) | 8.4 / 9 / 10 mm |
| Hex spanner size (ISO 4032) | 13 mm |
| Socket cap screw hex key (ISO 4762) | 6 mm |
Common questions
What size drill do I use to tap M8?
Use a 6.75 mm drill. This is the standard tap drill for M8; for hard materials or deep threads a slightly larger drill reduces tapping torque.
What is the pitch of M8?
The pitch of M8 is 1.25 mm (coarse), meaning the thread advances that distance in one full turn.
Where can I find other ISO Metric Coarse Thread sizes?
The full ISO Metric Coarse Thread table, with every size and a live filter, is on its standard page, and the Thread Finder searches all 73 standards at once.
Reference values; computed values use the ISO basic profile. Verify against the current standard before production use.