Enter a value in any length unit and instantly see the equivalent in millimeters, meters, kilometers, inches, feet, miles and more.
| Unit | Value |
|---|
Length is the measurement most people run into every day — road signs in kilometers or miles, a shelf that needs to fit in inches or centimeters, a shipping label with dimensions in an unfamiliar system. This tool lets you enter a value once and see it converted to every common length unit at the same time — metric, imperial, nautical, and even astronomical — no need to look up a from/to pair.
Every length unit converts through the meter (m), the SI base unit of length. To convert from unit A to unit B:
All length units are linear multiples of the meter, so every conversion here is straightforward multiplication or division — there's no offset to account for, unlike temperature scales.
| Unit | Symbol | Value in Meters |
|---|---|---|
| Nanometer | nm | 1 × 10⁻⁹ |
| Micrometer | μm | 1 × 10⁻⁶ |
| Millimeter | mm | 0.001 |
| Centimeter | cm | 0.01 |
| Meter | m | 1 |
| Kilometer | km | 1,000 |
| Mil (thou) | mil | 0.0000254 |
| Inch | in | 0.0254 |
| Foot | ft | 0.3048 |
| Yard | yd | 0.9144 |
| Mile | mi | 1,609.344 |
| Nautical Mile | nmi | 1,852 |
| Light-year | ly | 9.4607304725808 × 10¹⁵ |
Note: inch/foot/yard/mile use the exact international yard-and-pound definition (1959). The nautical mile is defined exactly as 1,852 m. The light-year uses the IAU-adopted Julian-year definition.
Example 1 — Miles to Kilometers
A road sign shows 5 miles to the next town: 5 × 1.609344 km/mi = 8.05 km.
Example 2 — Inches to Centimeters
A 15-inch laptop screen: 15 × 2.54 cm/in = 38.1 cm.
Example 3 — Millimeters to Mils
A machining tolerance of 0.05 mm: 0.05 mm ÷ 0.0254 mm/mil ≈ 1.97 mil — a common conversion in manufacturing drawings.
Example 4 — Light-years to Kilometers
The nearest star system, Proxima Centauri, is about 4.25 light-years away: 4.25 × 9.4607 × 10¹⁵ m ≈ 4.02 × 10¹³ km.