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Length Converter

Convert between metric and imperial units of length and distance — meters, feet, inches, miles and more.

0.39370079

1 cm = 0.39370079 in

Popular Length Conversions

About length units

Length is the measurement of distance along a line — how far apart two points are. It is one of the seven base quantities in physics, and almost every practical measurement you make day to day, from the height of a door frame to the distance of a commute, is a length. Because different parts of the world standardised on different systems, the same distance is written in metric units like meters and centimeters in most countries and in imperial units like feet, inches and miles in the United States and, for some purposes, the United Kingdom.

History & origin

The meter was originally defined in 1793 as one ten-millionth of the distance from the equator to the North Pole, and is now fixed by the speed of light. Imperial units grew out of older body-based measures: an inch was roughly the width of a thumb, a foot the length of a foot, and a yard the distance from nose to fingertip. Those historical roots are why the conversions are not round numbers — an inch is defined as exactly 2.54 centimeters, a value agreed internationally in 1959.

Tips

When converting, keep track of whether you need an exact or an everyday answer. For DIY and cooking, rounding an inch to 2.5 cm is usually fine; for engineering or shipping dimensions, use the full 2.54 factor. A common mistake is mixing up feet and yards — there are three feet in a yard, not ten — and forgetting that a nautical mile (1,852 m) is longer than a land mile (1,609 m).

Common questions

What is the difference between metric and imperial length units?
Metric units (millimeters, centimeters, meters, kilometers) scale by powers of ten, which makes mental math simple. Imperial units (inches, feet, yards, miles) come from historical measures and use irregular ratios like 12 inches to a foot and 5,280 feet to a mile.
Which countries still use feet and inches?
The United States uses imperial units for most everyday measurements. The United Kingdom uses a mix — miles for road distances and feet and inches for height — while nearly every other country uses the metric system.