Introduction
This Length Converter changes one length unit into another. Type a number, pick your units, and see the answer right away. You can convert inches to cm, feet to meters, miles to km, and many more.
The tool holds over 90 units. You get metric units like millimeters, centimeters, meters, and kilometers. You also get inches, feet, yards, and miles. It even covers nautical miles, light years, parsecs, and old units like furlongs and fathoms.
Both boxes work. Type in the left box to convert one way, or type in the right box to go backward. Use the swap button to flip the units fast.
Below the answer, you can see the steps that show how the math works. You also get your length listed in ten common units at once, plus a chart and a full table of every unit and its size in meters. Tap a popular conversion button to set things up with one click.
How to use our Length Converter Calculator
Type a length, pick the unit you have and the unit you want, and the calculator shows the converted answer, the formula, step-by-step math, your length in 10 common units, and a magnitude chart.
From: Type the length you want to convert, like 12 or 2.5. It must be 0 or more.
From Unit: Pick the unit your number is in now, such as inches, meters, or miles. Units are grouped by type, like Metric, Imperial, and Astronomical.
To: This box shows your answer. You can also type here to convert backward and the From box will update.
To Unit: Pick the unit you want the answer in, such as centimeters, feet, or kilometers.
Swap button: Click it to flip the two units, so feet to meters becomes meters to feet.
Convert button: Click it to run the math again. The answer also updates as you type.
Clear button: Click it to empty both boxes and set the units back to inches and centimeters.
Copy result button: Click it to copy the answer so you can paste it somewhere else.
Popular Conversions: Click any button, like cm to inches or km to miles, to set both units fast.
What Is Length Conversion?
Length is how long something is from one end to the other. We measure length with units like meters, feet, inches, and miles. Length conversion means changing a measurement from one unit to another without changing the real size of the thing. For example, 1 inch and 2.54 centimeters are the same length, just written in two different ways.
The Two Main Systems
Most length units belong to one of two groups:
- Metric (SI): millimeter, centimeter, meter, kilometer. Each step goes up or down by 10, 100, or 1,000, so the math is easy. Most of the world uses this system.
- Imperial / US customary: inch, foot, yard, mile. These units use numbers like 12 and 5,280, so they take a bit more work.
How Unit Conversion Works
Every length unit can be written as a number of meters. A foot is 0.3048 meters. A mile is 1,609.344 meters. To switch units, you turn your value into meters first, then divide by the size of the new unit. You can also do it in one step by multiplying by a conversion factor, which is just the first unit's meters divided by the second unit's meters.
Common Length Conversions
- 1 inch = 2.54 centimeters
- 1 foot = 12 inches = 0.3048 meters
- 1 yard = 3 feet = 0.9144 meters
- 1 mile = 5,280 feet = 1.609344 kilometers
- 1 meter = 100 centimeters = 1,000 millimeters
- 1 kilometer = 1,000 meters = 0.621371 miles
- 1 nautical mile = 1,852 meters
Special Units
Some units are made for very big or very small things. Sailors and pilots use the nautical mile, which is tied to the shape of the Earth. Astronomers use the light year (the distance light travels in one year, about 9.46 trillion kilometers), the astronomical unit (the distance from Earth to the Sun), and the parsec. Scientists who study atoms use the angstrom and the nanometer. Printers and designers use points and picas for type size.
Why Length Conversion Matters
Getting units right keeps projects safe and correct. Builders, engineers, sewers, runners, cooks, and students all move between metric and imperial numbers. A mix-up can waste money or ruin a design. NASA once lost a spacecraft because two teams used different units. Checking your conversion takes a second and saves a lot of trouble.