Thread Pitch Converter
Convert millimetres per thread to threads per inch (TPI), or convert back.
A QUICK WALKTHROUGH
How to use this tool
- Select whether the input is millimetres per thread or threads per inch.
- Enter the value and calculate the reciprocal conversion.
Formula and units
TPI = 25.4 / p; p = 25.4 / TPI. p is pitch in mm/thread; TPI is threads per inch. Both conversions use the exact factor 25.4.
Scope and limitations
Exact unit relationship only: 1 inch = 25.4 mm. Standard size matching is currently unavailable because no versioned, reliably licensed specification table is included. Conversion does not identify thread form, diameter, fit or compatibility.
Input limits and precision
Enter a finite value from 0.000000001 to 1,000,000. Results use floating-point arithmetic and display 12 significant digits; displayed digits are not measurement accuracy.
GOOD TO KNOW
Common questions
Are values uploaded?
Values stay in your browser and are not uploaded or stored.