Length Converter

This page converts a length from one unit into another. Every value passes through the metre, the SI unit length is held in, and length stays length: a unit only converts inside its own dimension.

How do you convert a length between metric and imperial units?

Pick the unit you have, pick the unit you want, and type the value. The page multiplies by the factor between the two and prints the arithmetic under the result, so the answer and the working are the same object.

1. Choose the unit your value is in. This page opens on the foot.
2. Choose the unit you want it in. This page opens on the metre.
3. Type the value. The result and the factor behind it appear together.
4. Read the working. It converts into the metre first and out again, which is the same two lines you would write by hand.

Length Conversion Table

One row per unit this page offers, each measured against the metre. The last column says whether the factor is a definition or a reading of one.

Worked Examples

The questions the bank ranked highest for this page, answered with the working.

Where These Factors Come From

Every number above is read from the knowledge base rather than computed for the page. These are the statements it holds for length.

• One inch is exactly 25.4 mm, one foot is exactly 0.3048 m, one yard is exactly 0.9144 m and one mile is exactly 1609.344 m.
• The international nautical mile is exactly 1852 m. It is a different unit from the statute mile of 1609.344 m and is used for distance at sea and in the air.
• An exact factor is a definition rather than a measurement. 1 in = 25.4 mm and 1 lb = 0.45359237 kg were fixed by the 1959 international yard and pound agreement, so they never gain another digit.
• How this page reports a result result in the target length unit, exact where the factor is exact, otherwise rounded to 10 significant figures

SI prefixes on this page

Which Foot and Which Mile?

This page uses the international foot, the international yard and the international mile, the definitions the International Yard and Pound Agreement fixed, and it lists the nautical mile as a unit of its own rather than a variant of the statute mile. The US survey foot is a separate definition and is not one of the units offered here.

The rule behind this factor is the same for every unit - what makes a factor exact.

Frequently Asked Questions

Related Conversions

• Angle sits in the same measurement group as length - angles in degrees, radians and gradians.
• Volume sits in the same measurement group as length - convert a volume between litres and gallons.
• Area sits in the same measurement group as length - convert an area between square metres and acres.
• If you are measuring parts-per ratio rather than length, a ratio written as parts per something instead.
• If you are measuring pressure rather than length, pressure in pascals, bar and atmospheres instead.
• If you are measuring mass rather than length, mass in kilograms, pounds, ounces and stone instead.

The rest of the family sits on another dimension to convert.