Inch fraction to mm

Convert decimal inches, simple fractions and mixed inch fractions to millimeters in one compact tool.

Result Enter an inch value or fraction.
Examples

How it is calculated

The inch value is converted to a decimal number first, then multiplied by 25.4 because 1 inch equals exactly 25.4 mm.

Common uses

  • Read workshop, hardware and product measurements written in inch fractions.
  • Convert drill bits, material thicknesses and small part dimensions.
  • Move between imperial catalogs and metric drawings.

Quick notes

Can I type mixed fractions?

Yes. Use values such as 1 3/8, 2-1/2, 3/16, 0.75 or 0,75.

Is 25.4 exact?

Yes. The international inch is defined as exactly 25.4 millimeters.