ISO Metric Coarse Thread · DIN 13-1 / ISO 261
M2.5 Thread: Pitch, Tap Drill & Dimensions
M2.5 is an ISO metric coarse thread with a 0.45 mm pitch. The tap drill is 2.05 mm, and the internal minor diameter D1 is 2.013 mm.
| Nominal (major) diameter | 2.5 mm |
|---|---|
| Pitch | 0.45 mm (coarse) |
| Tap drill (D − P) | 2.05 mm |
| Pitch diameter d2 / D2 | 2.208 mm |
| Minor diameter, external d3 | 1.948 mm |
| Minor diameter, internal D1 | 2.013 mm |
| Thread depth, external h3 | 0.276 mm |
| Flank angle | 60° |
| Clearance hole (fine / medium / coarse) | 2.7 / 2.9 / 3.1 mm |
| Hex spanner size (ISO 4032) | 5 mm |
| Socket cap screw hex key (ISO 4762) | 2 mm |
Common questions
What size drill do I use to tap M2.5?
Use a 2.05 mm drill. This is the standard tap drill for M2.5; for hard materials or deep threads a slightly larger drill reduces tapping torque.
What is the pitch of M2.5?
The pitch of M2.5 is 0.45 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.