Unit conversion basics

One measurement, different units

A distance can be described in kilometers, miles, meters or feet. The physical distance does not change when the unit changes; only the numerical representation changes.

Use the right quantity

Length, area and volume are different quantities. A length conversion factor cannot be used directly for an area measurement. Confirm what the number represents before converting it.

Rounding

Converted values are often rounded for display. Keep extra precision when an exact calculation requires it, then round at the end rather than repeatedly rounding intermediate values.

Try the Unit Converter for common length conversions.