Length Converter
A light-year is 9.46 trillion km. Just in case you needed to convert that.
About This Calculator
How It Works
All conversions route through meters as the universal base unit. Enter a value in any unit — millimeters, centimeters, meters, kilometers, inches, feet, yards, or miles — and the calculator instantly converts it to all the others simultaneously. This lets you see the same length across both metric and imperial systems at once, which is especially useful when working across systems that don't naturally speak to each other.
The Formula
Base unit: 1 meter. All conversions go through meters. 1 inch = 0.0254m. 1 foot = 0.3048m. 1 mile = 1609.344m.
When to Use This
This comes up constantly in international contexts: buying furniture with measurements in the wrong unit, following a recipe with metric ingredients when your measuring tools are imperial, reading product specs from another country, or doing construction with a mix of imperial plans and metric materials. It's also the fastest way to sanity-check a conversion you've done mentally.
Example
5 feet 10 inches = 177.8 cm = 1.778 m. If you've ever wondered your height in any unit, now you know the conversion path.
Did You Know?
A light-year is approximately 9.46 trillion kilometers or 5.88 trillion miles. The nearest star (Proxima Centauri) is 4.24 light-years away. Our length converter tops out at miles, but the universe had other plans.