Interactive / exact relationship

Thread Pitch and TPI Converter

Convert axial pitch in millimeters and thread count per inch. The result is a mathematical comparison, not a claim that metric and inch threads interchange.

Formula

TPI = 25.4 ÷ pitch in millimeters. The inverse is pitch in millimeters = 25.4 ÷ TPI. The 25.4 conversion factor is exact.

Limitations

Pitch equivalence does not establish diameter, profile, tolerance class or interchangeability. Confirm the complete thread standard and designation.