Length Converter
Convert between metric and imperial length units instantly. Enter a value and see it in all other units.
Last updated: August 2026 · Written and verified by Akash Pandey
Convert length
metres
This runs the same calculation engine as the main scientific calculator, entirely in your browser. Nothing you type is sent anywhere.
Why multiplying by a conversion factor works
A conversion factor such as 1 mile = 1.60934 km is a statement that two measurements describe the same physical length. Because 1.60934 km ÷ 1 mile equals exactly 1, multiplying a quantity by that ratio changes its units without changing what it measures - you are multiplying by 1, not by a number. This is why you can chain conversions (miles → metres → centimetres) and the answer never depends on which units you happened to pass through, as long as you keep track of which unit is on top.
value in unit B = value in unit A × (unit A per unit B)⁻¹
- Flip the ratio (invert it) if you convert in the other direction - this is the single most common source of a 3.28×-too-big or 3.28×-too-small answer.
- Since 1959, the international yard and pound agreement fixes 1 inch = 2.54 cm exactly, so every other imperial-to-metric length factor here (foot, mile) is exact, not a rounded measurement.
Metric vs imperial
The metric system is built from powers of 10 (metre, kilometre = 1000 m, centimetre = 1/100 m), so converting within it is just moving a decimal point. Imperial units grew from historical, human-scale references - the foot was literally a human foot before standardisation - which is why 1 foot = 12 inches and 1 mile = 5,280 feet look arbitrary: they were fixed by convention, not by base-10 structure.
Common length conversions
| From | To | Multiply by |
|---|---|---|
| Metres | Feet | 3.28084 |
| Feet | Metres | 0.3048 |
| Kilometres | Miles | 0.621371 |
| Miles | Kilometres | 1.60934 |
| Inches | Centimetres | 2.54 |
| Centimetres | Inches | 0.393701 |
Real-world uses
- Running and racing - a marathon is defined as exactly 26.219 miles (42.195 km); a 5K race is 3.107 miles.
- Travel - road signs, speed limits, and rental-car dashboards switch units at borders (US mph vs. everywhere-else km/h).
- Scale drawings and blueprints - an architect's 1:100 drawing needs every dimension converted consistently, or the building will not match the plan.
- Height and clothing sizes - "175 cm" and "5'9"" describe the same height; converting lets you compare across countries.
Worked examples
Convert a 5-mile race distance to kilometres
5 × 1.60934
- Given: 5 miles. We want the same distance in kilometres.
- Method: multiply by the miles-to-km factor, since we are converting from miles.
- Calculation:
5 × 1.60934 = 8.0467. - Interpretation: a "5-mile" fun run is a little over 8 km - useful for comparing against a metric-country race listing.
= 8.0467 km
A doorway is 203 cm tall. Will a 6-foot-8-inch (80 in) wardrobe fit through it upright?
80 × 2.54
- Convert the wardrobe height to centimetres so both figures share a unit:
80 × 2.54 = 203.2 cm. - Compare directly: 203.2 cm is taller than the 203 cm doorway.
- Interpretation: it will not fit upright - it is 0.2 cm (2 mm) too tall, which is exactly the kind of near-miss that unit mixing hides until you actually do the conversion.
= No - 203.2 cm > 203 cm
- Convert the wardrobe height to centimetres so both figures share a unit:
A common mistake: multiplying instead of dividing
The table above gives a factor for each direction because inverting the wrong way is the single most common error. If you have a value in feet and want metres, you multiply by 0.3048 (a small number, because metres are the bigger unit and you need fewer of them). Multiplying by 3.28084 instead - the feet-per-metre factor - inflates the answer by roughly 10.7×. A quick sanity check: converting a small-unit value (feet) to a large-unit value (metres) should make the number smaller, not larger.
Quick reference
| Object | Approximate length |
|---|---|
| Credit card | 8.56 cm / 3.37 in |
| A4 paper (width) | 21 cm / 8.27 in |
| Guitar | 1 m / 3.28 ft |
| Car | 4.5 m / 14.8 ft |
| Football field | 100 m / 328 ft |
- The same unity-fraction logic applies to weight
- Temperature does not convert this way - see why
- Scale drawings are really ratio problems
Frequently Asked Questions
Why is 1 inch defined as exactly 2.54 cm, with no rounding?
Before 1959, the US and British inch differed slightly. The International Yard and Pound Agreement fixed 1 yard = 0.9144 m exactly, which makes 1 inch = 2.54 cm exactly - a legal definition, not a rounded measurement, so every conversion built on it (feet, miles) is also exact.
I converted feet to metres and got a huge number - what went wrong?
You likely multiplied by the metres-to-feet factor (3.28084) instead of the feet-to-metres factor (0.3048). Converting a small unit (feet) into a larger unit (metres) should always produce a smaller number - if your answer grew instead of shrinking, the factor is inverted.
Why do the US and most of the world use different measurement systems?
The metric system was adopted by international treaty (the 1875 Metre Convention) for its base-10 structure. The US signed the same treaty but never legally mandated metric for everyday use, so imperial units persisted in US road, construction, and retail contexts even as science and medicine there use metric.
What is a nautical mile, and why is it different from a mile?
A nautical mile (1,852 m) is defined from the Earth's geometry: one minute of latitude along a meridian. A statute mile (1,609.344 m) comes from an old Roman/English land-measurement chain instead. They are unrelated definitions that happen to be similar sizes.
Does this converter handle area or volume, like square feet or cubic metres?
No - this tool converts one-dimensional length only. Converting an area requires squaring the length factor (1 ft² = 0.3048² m² ≈ 0.0929 m²), and volume requires cubing it - a detail worth checking manually if you convert room sizes or material quantities.
How do I convert kilometres to miles in my head?
A quick estimate: multiply kilometres by 0.6. For example, 10 km ≈ 6 miles. The exact factor is 0.621371, but 0.6 is close enough for mental maths.
What is the difference between a metre and a yard?
A metre is slightly longer: 1 metre ≈ 1.094 yards, or equivalently 1 yard = 0.9144 metres exactly. For rough estimates, treat them as similar, but for precise work the 9% difference matters.
Why do some countries still use imperial units?
Historical inertia and the cost of changing infrastructure. The US, UK, and a few other countries have deep roots in imperial for road signs, construction, and daily life, even as science and medicine universally use metric.