Formula
The international inch has been exactly 25.4 millimeters since the 1959 yard and pound agreement:
inches = millimeters / 25.4
Other length pairs are on the length converter. This page keeps one direction so the factor stays visible.
Assumptions
- The value can be zero and cannot be negative.
- The result is shown with up to six decimal places.
Worked example
25.4 millimeters equal 1 inch.
Input definitions
- Millimeters
- The length you want in inches.
Limitations
A historical survey inch can differ slightly from 25.4 millimeters. This page uses the international inch.
Questions
Why is 25.4 the factor?
One international inch is defined as 25.4 millimeters.
Does this convert centimeters?
No. Use the centimeters-to-inches page for that pair.