Quick answer: Length conversion uses exact definitions: one inch is exactly 2.54 centimeters, one foot is 30.48 centimeters, one yard is 0.9144 meters, and one mile is 1.60934 kilometers. Metric prefixes scale by powers of ten, so converting millimeters to kilometers just moves the decimal point six places.
Last reviewed: September 2026
Key facts
- 1 inch = 2.54 cm exactly and 1 foot = 0.3048 m exactly — defined by international agreement.
- 1 mile = 1.609344 km; 1 metre = 3.28084 feet.
- Shows every unit in a full table, so one conversion answers all follow-ups.
- Handy for DIY, travel, running distances and homework.
Metric to imperial, small to vast — length conversions come up in DIY, travel, school and sport. This free length converter translates between millimetres, centimetres, metres, kilometres, inches, feet, yards and miles instantly, with a full conversion table for every unit.
Enter a value and choose your units. Because imperial units are now defined exactly in metric terms, every conversion is precise.
How to use
- Enter a value.
- Choose the from and to units (swap them in one tap).
- See the answer plus every unit in the table below.
How length conversion works
| Term | Meaning |
|---|---|
| from-unit in metres | Each unit’s exact definition in metres. |
| to-unit in metres | The target unit’s definition in metres. |
The inch was fixed at exactly 2.54 cm by international agreement in 1959 — which makes the foot exactly 0.3048 m and the mile exactly 1,609.344 m.
Worked examples
Travel distances
1 mile → km: 1.60934 km.
100 m sprint → yards: 100 ÷ 0.9144 = 109.36 yd — why the 100 m dash is a little longer than 100 yards.
Height and DIY
6 ft → cm: 6 × 30.48 = 182.88 cm.
10 in → cm: 10 × 2.54 = 25.4 cm exactly.
Length units in metres
| Unit | Equals (m) | Think of |
|---|---|---|
| Millimetre (mm) | 0.001 | Thickness of a coin |
| Centimetre (cm) | 0.01 | Fingernail width |
| Metre (m) | 1 | A long stride |
| Kilometre (km) | 1,000 | 10–12 minute walk |
| Inch (in) | 0.0254 | Thumb width |
| Foot (ft) | 0.3048 | A school ruler |
| Yard (yd) | 0.9144 | A big step |
| Mile (mi) | 1,609.344 | ≈ 15–20 min walk |
Frequently asked questions
How many feet are in a metre?
3.28084 ft per metre (1 ft = 0.3048 m by international agreement).
How do I convert inches to centimetres?
Multiply inches by 2.54 exactly: 10 in = 25.4 cm.
What is bigger — a mile or a kilometre?
A mile (1.609 km) is longer than a kilometre. Roughly: 5 miles ≈ 8 km.
Why are there two definitions of a foot?
The international foot (0.3048 m) is standard; the old US survey foot differed by 2 parts per million and was retired in 2023.
How many cm in 5 ft 9 in?
5 × 30.48 + 9 × 2.54 = 152.4 + 22.86 = 175.26 cm.
Sources
Key takeaways
Key takeaways
- 1 in = 2.54 cm and 1 ft = 0.3048 m, exactly — by international agreement.
- 1 mile = 1.609344 km; 1 m = 3.28084 ft.
- The full table under the converter answers every follow-up conversion at once.
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