Length Converter
Type a value on either side and the other updates instantly — swap the units anytime, or scan the table below to see the same value in everything at once.
All units at once
The "From" value converted to every unit.
| Unit | Value |
|---|
How this converter works
Every unit here is stored as a single factor relative to meters: a millimeter is 0.001 m, a mile is exactly 1,609.344 m, and so on. Converting anything to anything else is two multiplications — value in the source unit times its factor gets you meters, then meters divided by the target unit's factor gets you the answer. That's why the numbers here are exact conversion factors, not rounded approximations: an inch is defined as exactly 0.0254 m by international agreement, so 1 inch converts to 2.54 cm on the nose, every time.
Worked example
The default above converts 10 feet to meters: 10 × 0.3048 = 3.048 m. Flip it with the swap button and 3.048 m back to feet returns exactly 10 — conversion and its inverse always round-trip cleanly because both directions use the same stored factor, just multiplying instead of dividing.
Frequently asked questions
How accurate are these conversions?
Exact, to the limits of floating-point math. Every unit converts through meters using the internationally defined factors — the inch is defined as exactly 0.0254 m, the mile as exactly 1609.344 m — so results aren't approximations rounded for convenience, they're the same numbers a calculator would give you.
Why convert through meters instead of directly between units?
It's simpler and just as accurate. Storing one factor per unit (relative to meters) instead of a factor for every possible pair means converting feet to yards is really feet → meters → yards behind the scenes — invisible to you, but it's why adding a new unit only ever needs one new number instead of seven.
What's the difference between a US mile and a nautical mile?
This tool converts the standard (statute) mile, 1,609.344 m, which is what road signs and car odometers use. A nautical mile is a different unit entirely — 1,852 m, based on one minute of latitude — used in aviation and maritime navigation. If you're converting flight or shipping distances, you want a nautical-mile converter, not this one.
Why does the reference table show so many decimal places for some units?
Some conversions are naturally tiny numbers — a millimeter is a very small fraction of a mile — so the table keeps enough significant digits that the value never rounds away to zero. It's the same underlying precision as the main result, just spread across every unit at once.