Length Unit Converter
Convert between every length unit in one place. Pick any two units, see the exact factor and the worked calculation.
How to use it
- Choose the unit you have and the unit you want.
- Type a value — the conversion is instant and shows the working underneath.
- Swap flips the two units. The URL always reflects what you see.
This converter covers every common length unit in one page rather than one fixed pair, so you are not hunting for a specific "X to Y" page when the two units you need are not the ones most people search for.
Pick the unit you have, the unit you want, and type a value — the result and the conversion factor both update immediately, worked out to full precision rather than a rounded rule of thumb.
Length units on this page
| Unit | Symbol | Notes |
|---|---|---|
| Nanometer | nm | Wavelengths of light, semiconductor process sizes and molecular dimensions. |
| Micrometer | µm | Filter ratings, machining tolerances, cell biology and particulate pollution. |
| Millimeter | mm | Engineering drawings, timber and steel sizes, rainfall and screen bezels. |
| Centimeter | cm | Body measurements, clothing sizes, paper and furniture dimensions across most of the world. |
| Meter | m | Room sizes, fabric, athletics tracks and almost all scientific work. |
| Kilometer | km | Road distances, running events and map scales outside the US and UK. |
| Inch | in | Screen sizes, pipe and tyre diameters, and construction in the US. |
| Foot | ft | Heights, room dimensions, aviation altitude and property listings in the US and UK. |
| Yard | yd | Fabric, American football, and landscaping materials. |
| Mile | mi | Road distances and speed limits in the US and UK. |
| Nautical mile | nmi | Marine and air navigation, where it maps directly onto a chart. |
A worked example
1 nm = 1.000000e-12 km. That factor comes from each unit's fixed relationship to the dimension's base unit — nothing here is approximated or looked up from a rounded table.
Every pairing on this page uses the same approach, so a chain of conversions (say, millimetres to miles) stays accurate rather than compounding rounding error the way repeated approximate factors would.
Everything runs in your browser
There is no server involved in the calculation. The numbers you type never leave your device, nothing is logged, and the page keeps working with no connection once it has loaded. That is not a marketing line — it is simply how the tool is built, because a calculation like this has no reason to touch a network.
Last updated 18 August 2026