Length Calculator
Convert length and distance between meters, centimeters, inches, feet, yards, miles, nautical miles, light-years and more, all updating as you type. Exact definitions such as 1 in = 2.54 cm and 1 nmi = 1,852 m are used, and the unit list can be reordered by dragging.
What does the Length Calculator do?
It converts one length into 18 units at once: metric (nm to Mm), US customary / imperial (inch, hand, foot, yard, chain, furlong, mile), nautical (nautical mile, fathom) and astronomical (au, light-year, parsec). Type a value in any row and every other row is recalculated with high-precision decimal arithmetic in your browser.
How to use
- Type a number into the row of the unit you know, for example 6 in Foot. All other rows update immediately (1.8288 m, 72 in, 2 yd, ...).
- Change rounding digits to control how many decimal places are shown (0 to 20).
- Toggle Separators for thousands separators, Ratio to show how each unit compares to the top row, and Description to show each unit's definition.
- Drag the handle on the left of a row to reorder units. The top row is marked (base unit) and is used for the ratios.
- In any row, press the Up / Down arrow keys to add or subtract 1 of that unit.
Units and definitions
| Unit | Symbol | Definition |
|---|---|---|
| Nanometer / Millimeter / Centimeter | nm / mm / cm | 10⁻⁹ m / 0.001 m / 0.01 m |
| Kilometer / Megameter | km / Mm | 1,000 m / 1,000,000 m |
| Inch | in | 2.54 cm (exact) |
| Hand | hh | 4 in (used for horse height) |
| Foot | ft | 12 in = 0.3048 m |
| Yard | yd | 3 ft = 0.9144 m |
| Chain / Furlong | ch / fur | 66 ft / 660 ft |
| Mile | mi | 5,280 ft = 1,609.344 m |
| Nautical mile | nmi | 1,852 m (exact) |
| Fathom | fth | 6 ft = 1.8288 m |
| Astronomical unit | au | 149,597,870,700 m (exact) |
| Light-year | ly | Distance light travels in a Julian year (365.25 days) |
| Parsec | pc | 648,000/π au ≈ 3.2616 ly |
Conversion examples
- 1 m = 39.3701 in = 3.28084 ft
- 1 mi = 1.609344 km = 1,760 yd = 80 ch
- 1 nmi = 1.852 km ≈ 1.15078 mi
- A marathon, 42.195 km ≈ 26.2188 mi
- 1 ly ≈ 63,241.08 au; 1 pc ≈ 3.26156 ly
Features
- 18 length units from nanometers to parsecs in one list
- Two-way conversion: any row can be the input
- Decimal arithmetic with 40 significant digits, so exact factors stay exact
- Very small results that would round to 0 are shown with significant digits instead
- Unit order, the last value and display options are remembered in this browser
FAQ
Is the mile here the US survey mile?
No. The mile is the international mile of 1,609.344 m. The old US survey mile (about 1,609.347 m) is not included.
Why does a value show as 0 or with fewer decimals than I expect?
Values are rounded to the rounding digits setting. Increase it to see more decimals. A non-zero value that would round to 0 is shown with significant digits instead.
Is my input sent anywhere?
No. All conversions run in your browser; the value and settings are only stored locally so they are still there next time.