How to Measure Thread Pitch
Measure thread pitch with a ruler, pitch gauge, or calipers—then use our thread identifier and pitch converter.
Using a thread pitch gauge
Match the gauge teeth to the thread. The gauge will read in TPI (imperial) or mm pitch (metric). This is the fastest method. If you then have diameter, use our thread identifier tool to get the full thread designation.
Measuring pitch without a gauge
| Method | How |
|---|---|
| TPI (imperial) | Count how many thread crests fit in 1 inch |
| Pitch in mm | Measure length of 10 threads (crest to crest), divide by 10 |
| Pitch in inches | 1 ÷ TPI (e.g. 20 TPI = 0.05 in pitch) |
Convert between pitch and TPI with our thread pitch to TPI converter.
Measuring diameter
Measure the major diameter (crest of thread) with calipers. For bolts, use the shank or the threaded portion; avoid damaged threads. Enter diameter and pitch into the thread identifier to get likely thread standards. Cross-check with a screw size chart or tap drill chart.
FAQ
How do you measure thread pitch?
Use a pitch gauge, or measure the distance over several threads and divide by the number of threads. For TPI, count threads in one inch.
How do you measure metric thread pitch?
Measure length over several crests in mm and divide by the number of threads, or use a metric pitch gauge. Then use our thread identifier.
What if I don't have a pitch gauge?
Count threads in 1 inch for TPI, or measure 10 threads and divide by 10 for pitch in mm. Use our thread identifier with diameter and pitch.