Length Converter

Convert length between eight metric and customary units, including meters, feet and miles, with adjustable precision and clear formulas.

Convert your value

Runs in your browser

Value to convert

Use a decimal point, without commas. Scientific notation such as 1e6 is accepted.

From unit

To unit

Swap exchanges the units and keeps your entered value.

Decimal places

Converted value

Foot (ft)

Displayed to 6 decimal places. Display rounding does not change the calculation.

Conversion formula

ft = m × 1 ÷ 0.3048

The factors express each unit in m. Negative inputs represent signed changes.

How to use Length Converter

Compare a product dimension in inches with a metric drawing, translate a walking distance from miles to kilometers, or express a small measurement in millimeters. This converter uses the international inch, foot, yard and mile; it does not use the retired US survey foot.

Enter a value, then choose the source and destination units. The result updates as you type.
Use Swap to exchange the units while keeping your input unchanged. Use ± to change the input sign.
Choose 0–10 decimal places for display. Copy result copies the displayed number and its unit.

How the conversion works

Multiply the input by its meter factor, then divide by the destination unit's meter factor. For example, an inch is exactly 0.0254 meters, so inches to centimeters uses 0.0254 ÷ 0.01 = 2.54.

Base-unit factors for length converter
Unit	One unit in m
Millimeter (mm)	0.001 m
Centimeter (cm)	0.01 m
Meter (m)	1 m
Kilometer (km)	1000 m
Inch (in)	0.0254 m
Foot (ft)	0.3048 m
Yard (yd)	0.9144 m
Mile (mi)	1609.344 m

1 foot = 12 inches; 1 yard = 3 feet; 1 mile = 1,760 yards.
Negative inputs are useful for signed distances or changes in position.

Calculations use browser number precision (about 15–16 significant digits). Extremely large or small results use scientific notation; values outside the numeric range show an error.

Reference: NIST unit conversion factors and temperature formulas. Squared and cubed units are derived from the international inch and foot; the acre uses 43,560 international square feet.

Practical examples

A 2.5-kilometer walk

Input: 2.5 km
Result: 2500 m

Multiply kilometers by 1,000 to express the route in meters.

A 12-inch shelf

Input: 12 in
Result: 30.48 cm

Each inch is exactly 2.54 centimeters, giving a 30.48-centimeter dimension.

A five-mile route

Input: 5 mi
Result: 8.04672 km

Each international mile is 1.609344 kilometers. The displayed value is rounded to five decimal places.

Frequently asked questions

Which standard foot and mile definition does this converter use?

This converter uses the international yard and pound definition established in 1959, where 1 inch is exactly 0.0254 meters, 1 foot is 0.3048 meters, and 1 international mile is 1,609.344 meters. It does not use the historical US Survey foot, which was officially deprecated for modern mapping.

Can I enter negative numbers for length conversions?

Yes. Negative values are supported to describe signed displacements, coordinate differences, elevation shifts, or relative position adjustments in technical and navigation applications.

How does display precision rounding work?

You can select display precision between 0 and 10 decimal places. Internal arithmetic uses full IEEE 754 floating-point accuracy (approximately 15–16 significant digits), and rounding half up is applied only to the final displayed text to prevent compounding errors.