Length Converter
Convert between millimetres, centimetres, metres, kilometres, inches, feet, yards and miles.
The length converter converts between metric and imperial units of distance. It is useful for travel, DIY projects, fabric measurements, fitness tracking and any time a value is given in a unit you do not think in.
How to use the converter
- Enter the value you want to convert.
- Choose the unit you have and the unit you want.
- Read the converted result instantly, along with a full conversion table.
- Swap the units to convert in the opposite direction.
How the conversion works
Result = value in metres ÷ factor of the target unit
Worked example
1 metre to feet
1 metre ÷ 0.3048 = 3.2808 feet
Or reverse it: 1 foot = 0.3048 metres, so 6 feet is about 1.83 metres.
Popular conversions
Jump straight to a single conversion, or use the converter above for any pair.
Who should use this length converter
- Travellers reading distances, heights or luggage limits in units they do not think in.
- Anyone doing DIY, carpentry or tailoring where a plan is in inches and the tape measure is in centimetres.
- Students converting measurements for assignments, drawings or specifications.
- Online shoppers buying fabric, cables or furniture from a site that lists sizes in another system.
Common mistakes to avoid
- Reading feet and inches as a decimal. Five feet ten inches is 5.83 feet, or about 177.8 cm. Writing it as 5.10 feet introduces a ten-inch error.
- Using 2.5 cm for an inch in precise work. The exact definition is 2.54 cm. Over a metre of material the approximation is off by more than a centimetre.
- Rounding too early in a chain of conversions. Convert through the base unit and round only at the end, or the small errors multiply.
- Assuming US and imperial lengths differ. Unlike gallons, inches, feet, yards and miles are identical in both systems. Only volume units diverge.
- Mixing metres with feet in one plan. A single drawing in two systems is the most common source of expensive DIY mistakes.
Why metric is easier to work with
Every metric length unit sits a power of ten away from the next: 1,000 millimetres to a metre, 1,000 metres to a kilometre. Converting means moving a decimal point, which is why science and most of the world uses it. Imperial units follow no such pattern — 12 inches in a foot, 3 feet in a yard and 1,760 yards in a mile. There is no mental shortcut between them.
The bridge between the two systems is fixed by definition rather than by measurement: one inch is exactly 2.54 centimetres. That single number is why this converter can be accurate to six decimal places, and why converting between any two units is really just two multiplications — into the base unit and back out again.
Length units explained
- Metre
- The SI base unit of length, defined by the distance light travels in a fraction of a second.
- Inch
- Exactly 2.54 centimetres by international agreement since 1959.
- Foot
- Twelve inches, or 30.48 centimetres. Still the standard for height and construction in several countries.
- Statute mile
- 1,609.344 metres — the mile used for road distances in the US and UK.
- Nautical mile
- 1,852 metres, based on one minute of latitude. It is not the same as a statute mile and is used at sea and in aviation.
Reading a tape measure in both systems
Most tape measures have centimetres on one edge and inches on the other, which is useful and easy to misread. Pick one edge and stay with it for the whole job, then convert only the final figure. If a plan mixes systems, convert everything into the one your cutting tools use before you mark anything.
Nominal sizes also catch people out. Timber sold as two by four inches is usually finished to about 1.5 by 3.5 inches, and plywood sold as three-quarter inch is often 18 mm. The label describes the rough or trade size rather than the measured one, so check the actual dimensions before designing around them.
Frequently asked questions
How many inches are in a foot?
There are exactly 12 inches in a foot, and 3 feet in a yard. One inch equals 2.54 centimetres, which is the fixed definition the whole imperial system is based on.
How do I convert kilometres to miles?
Multiply kilometres by 0.621371, or divide by 1.609344. A 10 km run is about 6.21 miles, which is why 5 km and 10 km races are often called 3.1 and 6.2 mile races.
Why is the metric system easier?
Metric units scale by powers of ten, so converting between mm, cm, m and km is a matter of moving the decimal point. Imperial units use irregular factors like 12 inches and 5280 feet per mile.