Thread Pitch Explained
What is thread pitch, metric thread pitch meaning, and TPI vs pitch. Quick reference for mechanics and machinists.
What is thread pitch?
Thread pitch is the distance from one thread crest to the next, measured along the axis. In metric threads it's given in millimeters (e.g. M8 x 1.25 means 1.25 mm pitch). In imperial systems it's often expressed as threads per inch (TPI)—higher TPI means finer threads. Use our thread pitch to TPI converter to switch between units.
Metric thread pitch vs imperial TPI
| Metric (pitch mm) | Imperial (TPI) | Notes |
|---|---|---|
| 1.0 | 25.4 | Coarse metric |
| 1.25 | 20.3 | Common M8 |
| 1.5 | 16.9 | Coarse M10 |
| 1.75 | 14.5 | Coarse M12 |
Why pitch matters
Wrong pitch causes cross-threading, stripped threads, or joint failure. Always verify pitch when replacing fasteners or tapping holes. The thread identifier tool matches diameter and pitch to common standards.
FAQ
What is thread pitch?
The distance from one thread crest to the next. Metric in mm (e.g. 1.25 mm); imperial often as TPI.
What is the difference between TPI and pitch?
TPI = threads per inch. Pitch = 1/TPI in inches, or directly in mm for metric. So 20 TPI = 0.05 in pitch.
How do I find metric thread pitch?
It's in the designation (e.g. M8 x 1.25). Or measure with a pitch gauge and use our thread identifier.