Unit Converter Convert length, weight, temperature and more — free, fast, private.

Length Converter

Convert millimeters, centimeters, meters, kilometers, inches, feet, yards and miles — live results as you type.

How length conversion works

Metric length units are decimal multiples of the meter; imperial and US units use fixed historical ratios (12 inches per foot, 1,760 yards per mile). The factor table below shows every unit against the meter, so you can convert by hand — multiply by the source factor, divide by the target factor — or just use the calculator above.

UnitEquals
1 Millimeter (mm)0.001 m
1 Centimeter (cm)0.01 m
1 Meter (m)base unit
1 Kilometer (km)1000 m
1 Inch (in)0.0254 m
1 Foot (ft)0.3048 m
1 Yard (yd)0.9144 m
1 Mile (mi)1609.34 m

All length conversions

Every length pair has its own quick-reference page with a conversion table:

Back to the full unit converter for all seven categories.

Common mistakes to avoid

A quick accuracy check

Want to sanity-check any converter? Convert -40 from Celsius to Fahrenheit: the result must be exactly -40, the only temperature where the two scales meet. Then convert 0 Kelvin to Celsius: you should get -273.15, absolute zero. A converter that handles both edge cases correctly has sound temperature formulas, and this one does.

Frequently asked questions

How many centimeters are in an inch?

Exactly 2.54 cm. The inch has been defined as exactly 25.4 mm since 1959, so every inch-based conversion here is exact rather than approximate.

What is the difference between metric and imperial length units?

Metric units (mm, cm, m, km) scale by powers of ten, so converting between them only moves the decimal point. Imperial units (inches, feet, yards, miles) use fixed ratios: 12 inches = 1 foot, 3 feet = 1 yard, 1,760 yards = 1 mile.