FT to MM Converter

A foot is 304.8 millimetres

Exactly, because an inch is exactly 25.4 mm and there are twelve of them to the foot.

1 ft = 304.8 mm exactly

The foot

Twelve inches, and exactly 0.3048 metres by international agreement. The twelve is the useful part: it divides by 2, 3, 4 and 6, which is easier for dividing a length by eye than a base-ten unit.

It remains standard for human height, building dimensions and aviation altitude — flight levels are in feet almost everywhere in the world, including countries that use metres for everything else.

The millimetre

A thousandth of a metre, and the working unit of engineering drawings, carpentry and anything made to fit. Metric technical drawings are dimensioned in millimetres by default, with no unit written at all.

It is close to the smallest length most people can judge by eye, which is part of why it has stayed the practical unit for made things.

The working, step by step

Every line updates with whatever you type above. The point is the method, which is the same for any pair of units in this family.

Copy the working

The same quantity, two different numbers

One physical amount, read off two scales. The tick marks do not line up, and the gap between them is the conversion factor made visible.

How much is that?

A number is easier to judge next to something familiar.

Your turn

Reading a method and being able to use it are different things. Answer within half a per cent and it counts as correct.

How to use this converter

1. Type into either box. The other side updates as you go; there is no button to press.
2. Swap the direction with the button between the boxes, carrying your value across.
3. Set the decimals if the default is more or less precision than you need.
4. Copy the answer with its unit, ready to paste.
5. Use the shortcut buttons for the values that come up most often.
6. Share the result. The address bar tracks what you type, so the link you copy opens on the same number.

Common uses and tips

Where length conversions come up

• Height. Quoted in feet and inches in Britain and America, and in centimetres nearly everywhere else. 5 ft 10 in is 178 cm.
• Buying things online from another market, where the dimensions are in units your tape measure does not have.
• DIY and building, where materials come in metric sizes and older plans are in imperial.
• Screens, tyres and pipes, which stay in inches worldwide even in fully metric countries.
• Running and cycling, where race distances are metric and training apps may report either.

Numbers worth carrying

• 1 inch = 2.54 cm exactly. Everything imperial in this family descends from it.
• 1 foot = 30.48 cm, twelve inches.
• 1 yard = 0.9144 m, a little shorter than a metre.
• 1 mile = 1.609 km, and 1 km = 0.621 mile.
• A metre is about 39.37 inches, or 3 ft 3 in.

Mental shortcuts

Kilometres to miles: multiply by six and drop the last digit. 80 km × 6 = 480, drop the digit for 48 miles, against a true 49.7.

Miles to kilometres: add sixty per cent. 50 miles plus 60 % is 80 km, against a true 80.5.

Centimetres to inches: divide by 2.5 and take off a little. Dividing by 2.5 gives an answer about 1.6 % high.

Mistakes worth avoiding

• Feet and inches are not decimal. 5.5 feet is 5 ft 6 in, not 5 ft 5 in. Multiply the decimal part by twelve.
• Do not use length factors for area or volume. A foot is 0.3048 m, but a square foot is 0.0929 m² and a cubic foot 0.0283 m³.
• Check which mile. A nautical mile is 1,852 m, about 15 % longer than a statute mile.

Values people look up most

Each one opens the converter with the number already in it.

• 1 ft to mm
• 2 ft to mm
• 4 ft to mm
• 6 ft to mm
• 8 ft to mm
• 10 ft to mm
• 20 ft to mm
• 50 ft to mm
• 100 ft to mm

Quick reference

Feet	Millimetres
1 ft	304.8 mm
2 ft	609.6 mm
6 ft	1,828.8 mm
8 ft	2,438.4 mm
10 ft	3,048 mm
100 ft	30,480 mm

Questions people ask

How many mm in a foot?

Exactly 304.8.

What is 6 ft in mm?

1,828.8 mm.