Length Converter
Convert between millimetres, centimetres, metres, kilometres, inches, feet, yards, miles, and more.
Result
—
—
All conversions
What is Length Converter?
A length converter lets you instantly convert a distance or size measurement from one unit to another. Length is a fundamental physical quantity measured in SI units (metres) as well as imperial and US customary units like feet and inches. Conversions are needed whenever you work across systems — for example, reading a blueprint in millimetres while your tape measure shows inches.
How to use
- 1 Enter the numeric value you want to convert in the Value field.
- 2 Select the unit you are converting from in the From dropdown.
- 3 Select the unit you want to convert to in the To dropdown.
- 4 The result appears instantly below the inputs.
- 5 Use the swap button to reverse the conversion direction.
Formula
Example calculation
To convert 5 miles to kilometres: 5 miles × 1609.344 m/mi = 8046.72 m, then 8046.72 m / 1000 m/km = 8.047 km. So 5 miles is approximately 8.05 kilometres.
Frequently asked questions
How many centimetres are in an inch?
There are exactly 2.54 centimetres in one inch. This is the defined relationship between the metric and imperial length systems.
What is the difference between a nautical mile and a regular mile?
A nautical mile is 1852 metres, while a statute mile is 1609.344 metres. Nautical miles are used in aviation and maritime navigation because one nautical mile equals one arcminute of latitude.
How do I convert feet and inches to centimetres?
First convert feet to inches (1 ft = 12 in), add your remaining inches, then multiply the total inches by 2.54 to get centimetres. For example, 5 ft 9 in = 69 in = 175.26 cm.
What is a light year in kilometres?
One light year is approximately 9.461 × 10^12 kilometres. It is the distance light travels in one year in a vacuum and is used to express astronomical distances.
Why does the converter show scientific notation for some results?
When a result is extremely large or very close to zero, scientific notation keeps the display readable. For example, converting 1 metre to light years gives roughly 1.057 × 10^-16 ly.