Length Unit Converter
Convert between millimeters, centimeters, meters, kilometers, inches, feet, yards, and miles.
About this tool
Length conversions between metric and imperial systems are among the most searched calculations on the web, and among the easiest to get wrong from memory. This converter uses exact international definitions: one inch is exactly 25.4 millimeters, from which every other conversion follows.
Results are shown to eight significant digits, which is more precision than any practical measurement requires. For everyday use, rounding to two or three decimal places is almost always sufficient.
Frequently asked questions
Are these conversions exact?
Yes. Since 1959 the international yard and pound agreement defines the inch as exactly 25.4 mm, making all length conversions between the systems exact.
Why does my answer differ slightly from another site?
Some sites round intermediate steps. This converter performs a single conversion through meters and rounds only the final result.