Convert Turns per Meter to Turns per Inch (TPM to TPI)
1 turn per metre (TPM) = 0.0254 turns per inch (TPI). 1 TPI = 39.37007874 TPM. Example: 600 TPM = 600 × 0.0254 = 15.24 TPI.
Also searched as turns per metre to TPI, turns per metre in TPI, turns per metre into turns per inch, TPM to TPI, TPM in turns per inch, TPM into turn per inch, turn per metre to turn per inch, TPM to turns per inch converter, turns per meter to turns per inch and how many turns per inch in a turn per metre.
1 TPM = 0.0254 TPI
Type in either box. Scientific notation works: 1.5e-3.
Converting a list? Use the bulk turn per metre to turn per inch converter to paste a column from Excel.
How to Convert Turn per Meter to Turn per Inch
- 1 TPM = 0.0254 TPI
- 1 TPI = 39.37007874 TPM
- Example: convert 600 TPM to TPI: 600 TPM = 600 × 0.0254 TPI = 15.24 TPI
Formula
TPI = TPM × 0.0254
or TPI = TPM ÷ 39.37007874016
Derivation from SI units:
- The SI-based unit of twist: complete turns of the yarn about its axis per metre of length.
- 1 TPI = 1 turn per 0.0254 m = 39.37007874 TPM (exact)
Both units are defined exactly, so the factor is exact. Turn per Meter definition: turn per metre; Turn per Inch definition: turn per inch.
Worked examples
- A ring-spun yarn with 600 TPM has 15.24 TPI.
600 TPM × 0.0254 = 15.24 TPI - A warp yarn with 800 TPM has 20.32 TPI.
800 TPM × 0.0254 = 20.32 TPI
Turn per Meter to Turn per Inch conversion table
| Turns per Meter (TPM) | Turns per Inch (TPI) |
|---|---|
| 100 TPM | 2.54 TPI |
| 200 TPM | 5.08 TPI |
| 300 TPM | 7.62 TPI |
| 400 TPM | 10.16 TPI |
| 500 TPM | 12.7 TPI |
| 600 TPM | 15.24 TPI |
| 700 TPM | 17.78 TPI |
| 800 TPM | 20.32 TPI |
| 1000 TPM | 25.4 TPI |
| 1200 TPM | 30.48 TPI |
Where it's used
Twist in turns per metre from metric specifications and twist testers is converted to turns per inch for cotton-system calculations and the English twist multiplier. Divide by 39.37.
Turn per Meter to other yarn twist units
| Conversion | 1 TPM equals |
|---|---|
| turn per metre to turn per inch | 0.0254 TPI |
| turn per metre to turn per centimetre | 0.01 TPcm |
| turn per metre to turn per foot | 0.3048 TPF |
Frequently asked questions
How many TPI is 1000 TPM?
1000 TPM = 25.4 TPI; divide TPM by 39.3701.
How many turns per inch are in 1 turn per metre?
1 TPM = 0.0254 TPI.
How do I convert turns per metre to turns per inch?
Multiply the value in TPM by 0.0254, or divide it by 39.37007874. For example, 600 TPM × 0.0254 = 15.24 TPI.
Is the TPM to TPI conversion exact?
Yes. Both units are defined exactly, and 1 TPM is exactly 0.0254 TPI.
Sources
- ISO 1144, Textiles — Universal system for designating linear density (Tex System), International Organization for Standardization , Metric designation of yarn twist.
- Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 Edition, National Institute of Standards and Technology , Appendix B.8, "inch".
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
Cite this page
APA
Scientific Converters. (2026, October 15). Convert Turns per Meter to Turns per Inch (TPM to TPI). Retrieved October 25, 2026, from https://scientificconverters.com/yarn-twist/turns-per-meter-to-turns-per-inch/
IEEE
Scientific Converters, "Convert Turns per Meter to Turns per Inch (TPM to TPI)," scientificconverters.com. Accessed: Oct. 25, 2026. [Online]. Available: https://scientificconverters.com/yarn-twist/turns-per-meter-to-turns-per-inch/