Length converter
Convert a length between metric and imperial units — metres, feet, miles, kilometres, inches, centimetres, yards and millimetres — all at once.
Exact conversion factors. Results rounded to three decimals.
How this calculator works
Length conversions rely on a small set of exact definitions. The metre is the SI base unit; the inch is defined as exactly 25.4 millimetres, which fixes the foot (12 inches = 304.8 mm), the yard (0.9144 m) and the mile (1,609.344 m). Kilometres are 1,000 metres and centimetres are one hundredth of a metre. Because these are definitions rather than roundings, conversions between metric and imperial lengths are exact to the number of decimals displayed.
The most common source of error is mixing up the direction of the conversion: multiplying by 3.28 when you meant to divide (for example converting feet to metres). The calculator computes a base value in metres first, then converts that base to every other unit, so one entry produces the full set of equivalents at once. Navigation, DIY and travel planning are the usual use cases; for surveying and engineering, keep more decimal places than the three shown here.
The formula
Convert to metres, then out of metres:
metres = value × factor(from)
result = metres / factor(to)
1 in = 0.0254 m 1 ft = 0.3048 m
1 yd = 0.9144 m 1 mi = 1,609.344 m
1 km = 1,000 m 1 cm = 0.01 mSo 100 m = 328.084 ft = 0.062 mi = 0.1 km = 3,937.008 in = 10,000 cm.
Worked example
Converting 100 Metres gives 328.084 ft in feet, 0.062 mi in miles and 0.100 km in kilometres. The same distance is also 3,937.008 in tall and 10,000.000 cm wide when split into smaller units.
Common mistakes
- Multiplying instead of dividing. Feet to metres divides by 3.281; metres to feet multiplies. Check that a metre is longer than a foot than a centimetre.
- Mixing inches and centimetres. Screen sizes and tools often mix units; convert everything to one unit before adding or comparing.
- Rounding mid-calculation. Round only at the end. Rounding each step can move a distance by several centimetres.
Frequently asked questions
How many feet in a metre?
One metre is 3.28084 feet. One foot is 0.3048 metres, so 100 m is 328.084 ft.
How many kilometres in a mile?
One mile is 1.609344 kilometres, and one kilometre is 0.621371 miles. A 5 km run is about 3.11 miles; a 10K is 6.21 miles.
How many inches in a centimetre?
One centimetre is 0.393701 inches, because the inch is exactly 2.54 cm. To go the other way, multiply inches by 2.54.
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