Threads per inch to threads per centimeter
Type a value in TPI to get it in threads/cm instantly.
7.874threads/cm
That's 1.27× as coarse as an M6 bolt, while an M10 bolt is 1.18× coarser. Ten millimeters of travel takes about 7.874 turns.
What it means
How coarse is that thread?
Pitch is only half the story: a thread also has a diameter and a flank angle. Metric threads use 60°, as do Unified threads, but British Whitworth uses 55°, so they never interchange.
The math
How to convert TPI to threads/cm
Pitch and threads per inch are reciprocals: mm = 25.4 ÷ TPI, and TPI = 25.4 ÷ mm. A finer thread means more threads per inch and a smaller pitch.
Example: 20 TPI = 7.87402 threads/cm.
Every unit
Your pitch in every unit
Tables
TPI to threads/cm conversion table
| TPI | threads/cm |
|---|---|
| 4 TPI | 1.5748 threads/cm |
| 6 TPI | 2.3622 threads/cm |
| 8 TPI | 3.14961 threads/cm |
| 10 TPI | 3.93701 threads/cm |
| 11 TPI | 4.33071 threads/cm |
| 13 TPI | 5.11811 threads/cm |
| 14 TPI | 5.51181 threads/cm |
| 16 TPI | 6.29921 threads/cm |
| 18 TPI | 7.08661 threads/cm |
| 20 TPI | 7.87402 threads/cm |
| 24 TPI | 9.44882 threads/cm |
| 28 TPI | 11.0236 threads/cm |
| 32 TPI | 12.5984 threads/cm |
| 40 TPI | 15.748 threads/cm |
threads/cm to TPI conversion table
| threads/cm | TPI |
|---|---|
| 4 threads/cm | 10.16 TPI |
| 6 threads/cm | 15.24 TPI |
| 8 threads/cm | 20.32 TPI |
| 10 threads/cm | 25.4 TPI |
| 11 threads/cm | 27.94 TPI |
| 13 threads/cm | 33.02 TPI |
| 14 threads/cm | 35.56 TPI |
| 16 threads/cm | 40.64 TPI |
| 18 threads/cm | 45.72 TPI |
| 20 threads/cm | 50.8 TPI |
| 24 threads/cm | 60.96 TPI |
| 28 threads/cm | 71.12 TPI |
| 32 threads/cm | 81.28 TPI |
| 40 threads/cm | 101.6 TPI |
Quick answers
Quick answers
- How many threads/cm is 1 TPI?
- 1 TPI is 0.393701 threads/cm.
- How many threads/cm is 10 TPI?
- 10 TPI is 3.93701 threads/cm.
- How many threads/cm is 20 TPI?
- 20 TPI is 7.87402 threads/cm.
The units
About these units
Threads per inch (TPI)
The imperial measure: how many threads fit in one inch.
Threads per centimeter (threads/cm)
A rarely used metric counterpart to TPI.
Keep going