Conversion library

Length Conversion Calculators

Choose a calculator for metric, imperial, typography, or screen measurements. Every page includes the formula, live calculation steps, and a common-values table.

All converters

How these length conversions work

Every calculator converts the source value to a shared base measurement, then converts that measurement to the selected target unit. Exact definitions such as 1 inch = 25.4 millimeters are used wherever they apply.

For the main conversion, use the millimeters to inches converter. For reverse calculations, use inches to millimeters.