Thread Pitch Explained
Thread pitch is the distance between adjacent thread crests. Metric threads use pitch in millimeters; imperial threads are often specified in threads per inch (TPI).
What is thread pitch?
Pitch is the axial distance from one thread crest to the next. For metric fasteners it is given in mm (e.g. M8 x 1.25 means 1.25 mm pitch). For imperial, TPI is common: 20 TPI means 20 threads per inch, so pitch = 1/20 inch.
Metric vs imperial pitch
| System | How pitch is given | Example |
|---|---|---|
| Metric | Pitch in mm | M8 × 1.25 |
| Imperial | TPI (threads per inch) | 1/4-20 (20 TPI) |
Convert between them with our Thread Pitch to TPI Converter.
Coarse vs fine threads
Coarse threads have larger pitch and are common for general use and soft materials. Fine threads have smaller pitch, more threads per length, and are used where strength in thin sections or fine adjustment is needed.
FAQ
What is thread pitch?
Thread pitch is the distance from one thread crest to the next, measured along the axis. Metric uses mm; imperial often uses threads per inch (TPI).
What is the difference between coarse and fine thread?
Coarse threads have larger pitch (fewer threads per length), better for soft materials and quick assembly. Fine threads have smaller pitch, better for thin walls and precision adjustment.
How do I convert thread pitch to TPI?
TPI = 25.4 divided by pitch in mm. Use our Thread Pitch to TPI Converter for instant conversion.
Related
Tools: Thread Pitch to TPI Converter, Thread Identifier
Charts: Universal Screw & Bolt Size Chart, Tap Drill Chart
Guide: What Is TPI