Conversions

Length Converter

What this does

Convert lengths and distances between metric and imperial units; millimeters through kilometers, inches, feet, yards and miles.

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Runs in your browser

Calculator inputs

How to use it

Using the length converter

  1. 01

    Type the amount

    Enter any positive number; decimals welcome.

  2. 02

    Pick both units

    Choose the unit you have and the unit you want.

  3. 03

    Read every equivalent

    The result shows your conversion plus the same distance in other common units.

Good to know

Metric meets imperial

The US customary system was redefined in 1959 so that one inch is exactly 2.54 centimeters. That agreement is why this converter can be exact rather than approximate; there is no fudge factor between the systems anymore.

Choosing sensible units

Match the unit to the scale: millimeters for machining, kilometers or miles for travel. A figure like “5,280 feet” is correct but hard to reason with; converting to miles restores intuition.

Precision you can trust

Internally the math uses full double precision and only the display rounds, so you can chain conversions through several tools without compounding rounding error.

How it's calculated

The math behind this calculator

result = value × factor(from) ÷ factor(to) Exact anchors: 1 inch = 0.0254 m, 1 mile = 1609.344 m

Every length converts to meters using the exact international definition of each unit, then divides by the target unit’s factor. Because both steps use precise constants, converting a result back reproduces the original input exactly.

Assumptions & limitations

  • Results are rounded only for display; full precision is used internally.
  • Conversions use exact standard definitions of each unit.

Worked example

One mile is exactly 1609.344 meters under the international yard-and-pound agreement.

FAQ

Frequently asked questions

How many feet are in a mile?
Exactly 5,280 feet, since one foot is 0.3048 m and one mile is 1609.344 m.
Is a US mile different from a nautical mile?
Yes. A nautical mile is 1852 m and is not among these units; knots measure speed over nautical miles in the speed converter.
Why does the result show extra digits?
Small amounts keep more decimal places so tiny conversions stay meaningful; large results trim trailing noise.

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