Home › Tap drill chart › M2.5 x 0.45
M2.5 x 0.45 tap drill size
Use a 2.05 mm drill to tap M2.5 x 0.45 (coarse pitch). The rule is major diameter minus pitch: 2.5 − 0.45 = 2.05 mm. Closest inch drill: #46 (2.06 mm).
M2.5 x 0.45 thread specifications
| Thread | M2.5 x 0.45 ISO metric coarse |
|---|---|
| Major (nominal) diameter | .0984 in / 2.50 mm |
| Pitch | 0.45 mm (≈ 56.4 threads per inch) |
| Recommended tap drill | 2.05 mm = .0807 in |
M2.5 clearance hole (ISO 273)
| Fit | Hole diameter |
|---|---|
| Fine (close) | 2.7 mm |
| Medium (normal) | 2.9 mm |
| Coarse (loose) | 3.1 mm |
A clearance hole lets the M2.5 bolt pass through freely. Drill the tap-drill size only in the part that gets threaded.
Tips for tapping M2.5 x 0.45
- Use cutting fluid, and with a hand tap back off about half a turn every turn or two to break the chip. Aluminium and soft materials are the exception: they tap cleanly with spiral-point taps.
- For blind holes, drill deeper than the thread you need. Allow at least 3–4 pitches beyond the last full thread for a plug tap (1.8 mm here).
- Thread engagement of 1–1.5 × the diameter (2.5–3.8 mm) is enough for most steel parts. Softer materials need more.