Length Converter — All Units

How to use this length converter

Enter your measurement, pick the unit you have, and pick the unit you need. The result appears instantly along with a reference table showing your measurement in all common units. Use the ⇄ button to reverse the conversion.

Understanding the length units

Metric units (millimetre, centimetre, metre, kilometre) are the international standard, used in science and in everyday life across most of the world. Each step is a factor of 10 or 1,000, which keeps mental conversion simple.

Imperial and US units (inch, foot, yard, mile) remain standard in the United States and are still widely used in the UK for road distances, heights, and building work. Since 1959 these units have been defined exactly in metric terms — one inch is exactly 2.54 centimetres — so conversions between the two systems are precise, not approximate.

The nautical mile (exactly 1,852 metres) is used in shipping and aviation. It's based on the Earth's geometry: one nautical mile is roughly one minute of latitude, which is why navigators have used it for centuries.

Frequently asked questions

How many centimetres are in an inch?
Exactly 2.54 cm. This is a defined value, not a rounded one. So 10 inches is exactly 25.4 cm.

How do I convert my height from feet and inches to centimetres?
First convert everything to inches (multiply feet by 12 and add the remaining inches), then multiply by 2.54. For example, 5 ft 9 in = 69 inches = 175.26 cm.

Why is a nautical mile longer than a regular mile?
A statute mile (1,609.344 m) comes from old Roman and English land measurement. A nautical mile (1,852 m) is based on the Earth's circumference — one minute of latitude — which makes it more practical for sea and air navigation.

Is a metre bigger than a yard?
Yes, slightly. One metre equals 1.09361 yards, or about 3.37 inches longer than a yard.

How accurate are the results?
All factors are exact international definitions, and results are rounded to six significant figures — more precision than any tape measure or GPS device can use.

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