# Length Conversion Calculators Convert one unit of length to another. Start by selecting the length unit to convert from.
US Customary & Imperial Units
SI Units

## What is Length?

Length is defined as a measurement of distance between two points.

It can also be defined as the distance of the longest horizontal dimension of an object, from end to end. If the object is a rectangle, length would be the distance of the longest edge of the rectangle.

Width is a the distance of the shortest horizontal dimension of an object. Height is considered the distance of the vertical dimension of an object and width is the distance of the shortest horizontal dimension of an object. Our length unit conversion tools will help you easily convert a length measurement from one unit to another, automatically. We have some similar measurement resources that you might also find interesting, such as our inch fraction calculator, printable tape measure, or our printable rulers.

## How to Convert a Length Measurement

To convert measurements of length from one unit to another, convert the unit to a base unit using a known conversion formula, then convert from the base unit to the target unit of measurement. For length, meters are commonly used base unit since the meter is the SI unit of length.

So, to convert a unit of length, start by converting the measurement to meters first. Next, convert from meters to the target unit of measurement.

For example, let's convert 18 inches to centimeters.

Step One: convert 18 inches to meters.

1 in = 0.0254 m
18 in = 18 × 0.0254 m
18 in = 18 × 0.4572 m

Step Two: convert 0.4572 meters to centimeters.

1 m = 100 cm
0.4572 m = 100 × 0.4572 m
0.4572 m = 45.75 cm

Thus, 18 inches is equal to 45.75 centimeters.

18 in = 45.75 cm

## Units of Length Measurement

Units of length include miles, yards, feet, inches, kilometers, meters, centimeters, millimeters, micrometers, and nanometers.

## Common Length Measurement Conversions

Miles to kilometers length conversion
1 mile is equal to 1.609344 kilometers
Kilometers to miles length conversion
1 kilometer is equal to 0.621371 miles
Feet to inches length conversion
1 foot is equal to 12 inches
Feet to meters length conversion
1 foot is equal to 0.3048 meters
Inches to centimeters length conversion
1 inch is equal to 2.54 centimeters
Centimeters to inches length conversion
1 centimeter is equal to 0.393701 inches

## Length Unit Conversion Table

Equivalent length metric and imperial measurements
Convert From Mile Yard Foot Inch Kilometer Meter Centimeter Millimeter Micrometer Nanometer
1 mile = 1 mi 1,760 yd 5,280 ft 63,360 in 1.609344 km 1,609 m 160,934 cm 1,609,344 mm 1,609,344,000 µm 1,609,344,000,000 nm
1 yard = 0.000568 mi 1 yd 3 ft 36 in 0.000914 km 0.9144 m 91.44 cm 914.4 mm 914,400 µm 914,400,000 nm
1 foot = 0.000189 mi 0.333333 yd 1 ft 12 in 0.000305 km 0.3048 m 30.48 cm 304.8 mm 304,800 µm 304,800,000 nm
1 inch = 0.000015783 mi 0.027778 yd 0.083333 ft 1 in 0.0000254 km 0.0254 m 2.54 cm 25.4 mm 25,400 µm 25,400,000 nm
1 kilometer = 0.621371 mi 1,094 yd 3,281 ft 39,370 in 1 km 1,000 m 100,000 cm 1,000,000 mm 1,000,000,000 µm 1,000,000,000,000 nm
1 meter = 0.000621 mi 1.093613 yd 3.28084 ft 39.370079 in 0.001 km 1 m 100 cm 1,000 mm 1,000,000 µm 1,000,000,000 nm
1 centimeter = 0.0000062137 mi 0.010936 yd 0.032808 ft 0.393701 in 0.00001 km 0.01 m 1 cm 10 mm 10,000 µm 10,000,000 nm
1 millimeter = 0.00000062137 mi 0.001094 yd 0.003281 ft 0.03937 in 0.000001 km 0.001 m 0.1 cm 1 mm 1,000 µm 1,000,000 nm
1 micrometer = 0.00000000062137 mi 0.0000010936 yd 0.0000032808 ft 0.00003937 in 0.000000001 km 0.000001 m 0.0001 cm 0.001 mm 1 µm 1,000 nm
1 nanometer = 0.00000000000062137 mi 0.0000000010936 yd 0.0000000032808 ft 0.00000003937 in 0.000000000001 km 0.000000001 m 0.0000001 cm 0.000001 mm 0.001 µm 1 nm

## References

1. Weisstein, Eric W., Distance, MathWorld - A Wolfram Web Resource, http://mathworld.wolfram.com/Distance.html
2. Kenneth Butcher, Linda Crown, & Elizabeth J. Gentry, The International System of Units (SI) – Conversion Factors for General Use, National Institute of Standards and Technology, https://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication1038.pdf

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