Length Converter — Metric & Imperial Distance Units
This free length converter converts any value instantly across nine distance units: millimetres, centimetres, metres, kilometres, inches, feet, yards, miles, and light-years. All nine output values update live as you type — there is no button to click and no page to reload.
The converter is useful for everyday tasks like converting imperial measurements for international shipping, calculating distances for travel, solving maths or physics homework, or converting architectural drawings between metric and imperial scales.
Length Conversion Reference Table
Key conversion factors between common units (all relative to 1 metre):
| Unit | Symbol | In metres | System |
|---|---|---|---|
| Millimetre | mm | 0.001 m | Metric |
| Centimetre | cm | 0.01 m | Metric |
| Metre | m | 1 m (base) | Metric |
| Kilometre | km | 1,000 m | Metric |
| Inch | in | 0.0254 m | Imperial |
| Foot | ft | 0.3048 m | Imperial |
| Yard | yd | 0.9144 m | Imperial |
| Mile | mi | 1,609.344 m | Imperial |
| Light-year | ly | 9.461 × 10¹⁵ m | Astronomical |
Most Common Length Conversion Formulas
Metres → Feet
ft = m × 3.28084
Feet → Metres
m = ft × 0.3048
Km → Miles
mi = km × 0.621371
Miles → Km
km = mi × 1.60934
Inches → Cm
cm = in × 2.54
Cm → Inches
in = cm ÷ 2.54
Frequently Asked Questions
Multiply the number of metres by 3.28084. For example, 5 metres = 5 × 3.28084 = 16.4042 feet. Select "Metres" as the input unit in the converter and the feet result updates live.
There are exactly 5,280 feet in one mile. One mile is also equal to 1,760 yards, 1,609.344 metres, or 1.609344 kilometres.
The metric system (SI) uses metres as the base unit and builds on powers of 10 — millimetres, centimetres, kilometres. The imperial system uses inches, feet, yards, and miles, with different multipliers between each. Most countries use metric; the US, UK (for some purposes), and Myanmar still use imperial.
Exactly 2.54 centimetres equal one inch. This is the exact, internationally-agreed definition. So 1 foot (12 inches) = 30.48 cm and 1 yard (36 inches) = 91.44 cm.
One light-year is the distance light travels in one year in a vacuum: approximately 9.461 × 10¹² km (about 9.46 trillion kilometres or 5.88 trillion miles). Enter 1 and select light-years to see this number in the converter.
The converter uses exact or high-precision conversion factors based on the international definition of the metre. Results are shown to up to 8 significant figures. For most practical purposes this exceeds the precision of any physical measurement.
Yes. Use the unit dropdown to choose any source unit, then all nine outputs update instantly. You can also click the swap button to flip the from/to unit — the result becomes the new input automatically.
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