Length Converter
Turn any length into a different unit — metric or imperial — using exact international conversion factors.
Exact factors
Every conversion uses the official 1959 international definitions, so an inch is exactly 25.4 mm — never a rounded approximation.
Display rounding
Results are shown to six decimal places, so very small or very large conversions may round the last digit.
What is a length converter?
One value, any unit
A length converter changes a measurement from one unit into another — metres to feet, centimetres to inches, kilometres to miles, and back. It works by translating every unit through a single shared base, the metre, so any pair of units can be converted with one consistent rule. This tool covers nine common units across the metric and imperial systems, making it useful for DIY projects, travel, engineering, schoolwork, and anywhere measurements in different systems need to meet.
Each unit has an exact size in metres. To convert, the value is first turned into metres, then into the target unit.
Result = value × (metres per from-unit) ÷ (metres per to-unit)Because the conversion factors are exact international definitions — inch = 0.0254 m, foot = 0.3048 m, yard = 0.9144 m, mile = 1609.344 m, and nautical mile = 1852 m — the result is mathematically exact, limited only by how many decimal places are displayed. The same single rule handles every direction, so converting feet back to metres just swaps which factor divides.
Suppose you want to convert 1 metre into feet.
Find the base size
One metre is, by definition, 1 metre — the base unit itself.Divide by the target factor
A foot is 0.3048 metres, so 1 ÷ 0.3048 = 3.28084.Read the result
1 metre converts to about 3.28084 feet.
The converted figure is exact to the precision shown. Metric units (mm, cm, m, km) scale in powers of ten, so moving the decimal point is often enough between them, while imperial conversions rely on the fixed factors above. For everyday tasks like cutting material or reading a map, round the result to a sensible number of decimals; for engineering or scientific work, keep the full precision. The nautical mile, used in sea and air navigation, is longer than a land mile, so a distance that looks small in nautical miles is larger than it first appears.
The arithmetic is exact; the only limit is display precision.
Rounding and unit choice
Results are rounded to six decimal places, so converting between units that differ enormously in size — millimetres to kilometres, for example — can lose the last digits. The converter handles pure length only; it does not convert area or volume, which scale with the square and cube of the length factor. For legal, surveying, or precision-manufacturing work, always confirm against the governing standard for your field.