How to use the Length Converter
- Type the number you want to convert.
- Choose the unit you are converting from.
- Choose the unit you want the answer in.
- Read the converted value and the exact conversion rate, and use the reference table below for common values.
Formula used
Result = Value × (metres per source unit ÷ metres per target unit). 1 inch = 0.0254 m, 1 foot = 0.3048 m, 1 yard = 0.9144 m and 1 mile = 1609.344 m exactly.
Worked example
Here is the Length Converter worked through with the example values shown above, so you can check each step by hand.
| Inputs | |
|---|---|
| Value | 100 |
| From | Kilometre (km) |
| To | Mile (mi) |
| Result | |
| Converted value | 62.137119 |
| Conversion rate | 1 km = 0.62137119 mi |
Quick reference table
Common values converted with the units selected above.
| From | To |
|---|---|
| 1 km | 0.62137119 mi |
| 5 km | 3.106856 mi |
| 10 km | 6.2137119 mi |
| 50 km | 31.06856 mi |
| 100 km | 62.137119 mi |
| 1,000 km | 621.37119 mi |
Common length conversions
One inch is exactly 2.54 centimetres, one foot is exactly 0.3048 metres, one yard is exactly 0.9144 metres and one mile is exactly 1.609344 kilometres. These are fixed by definition, so the conversions are exact. For example, 100 km is 62.1371 miles and 1 mile is 1.6093 km.
Other quick ones: 1 metre is 3.2808 feet, 1 foot is 30.48 cm and 1 inch is 25.4 mm. A person who is 5 feet 10 inches tall is 70 inches, which is 177.8 cm.
How to convert in your head
To change kilometres to miles, multiply by about 0.62, or take the number, halve it and add a bit more. To change miles to kilometres, multiply by about 1.6. For feet to metres, multiply by about 0.3, and for inches to centimetres multiply by 2.5.
These shortcuts are close enough for travel and rough planning. Use the calculator whenever you need an exact figure, for example for a delivery form, a design or an exam.
Where each unit is used
Kilometres and metres are standard on Indian roads, maps and in school science. Feet and inches remain common for height, for the size of rooms, for television and phone screens, and for some construction materials. Miles are used on US and UK roads, and in running and cycling events. Yards appear mainly in cricket pitch and football contexts.
Mixing units has caused expensive mistakes in engineering and shipping, so write the unit next to every number you record.
A note on accuracy
The calculator shows up to eight significant digits, which is far more precision than most everyday tasks need. When you copy the result into a document, round it to a sensible number of digits, for example two decimals for centimetres or one decimal for miles.
The conversions assume the international units. Older or regional units with similar names, such as the nautical mile or historic local measures, are different and are not included.
Exact definitions and handy conversions
The international inch is exactly 25.4 mm, so a foot is exactly 30.48 cm, a yard is 0.9144 m and a mile is exactly 1.609344 km. A person who is 5 feet 10 inches tall is 70 inches, or 177.8 cm. A marathon of 42.195 km is about 26.2 miles, and a 5 km run is about 3.1 miles.
For rough mental conversions, a metre is a little more than a yard, a kilometre is about five eighths of a mile and an inch is about 2.5 cm. The nautical mile (1,852 m) used at sea is not included in this converter. When you convert measurements for building or manufacturing, keep the full precision until the final step.
Frequently asked questions
How many kilometres are in a mile?
One mile is exactly 1.609344 kilometres.
How many centimetres are in an inch?
One inch is exactly 2.54 centimetres.
How many feet are in a metre?
One metre is about 3.2808 feet.
How do I convert feet and inches to centimetres?
Convert everything to inches first (feet × 12 + inches), then multiply by 2.54. For 5 ft 10 in, that is 70 × 2.54 = 177.8 cm.
Are the conversions exact?
Yes for inch, foot, yard and mile, which are defined exactly in metres. The display is rounded to eight significant digits.
Can I convert negative or decimal values?
Yes. You can enter decimals, and the result updates as you type.
How many centimetres is 5 feet 10 inches?
177.8 cm. 5 ft 10 in is 70 inches, and 70 × 2.54 = 177.8.
This calculator gives estimates for information only. Actual figures from a bank, employer, tax authority or doctor may differ. It is not financial, tax, legal or medical advice.