Metric and imperial length, converted exactly
Turn inches into centimetres, feet into metres or kilometres into miles with the exact factors, not the rounded ones people quote from memory.
Length is where metric and imperial collide most often: furniture listed in inches, a running route in kilometres, a ceiling height in feet. This converter handles the six units those situations actually use.
The factors here are the defined ones. An inch is exactly 2.54 cm and a mile is exactly 1.609344 km, so distances stay accurate even when you scale them up.
What this calculator shows
- The converted length with enough precision for cutting, fitting and measuring
- Millimetres through kilometres alongside inches, feet and miles
- A live result, so you can nudge the input and watch the answer move
What to keep in mind
- Uses international units: 1 inch = 2.54 cm exactly, 1 mile = 1.609344 km exactly.
- US survey feet, still used in some American land records, differ very slightly and are not covered here.
FAQs
How many centimetres is 6 feet?
182.88 cm. Six feet is 72 inches, and each inch is 2.54 cm exactly. Height charts usually round this to 183 cm.
Why is 1 mile 1.609 km and not 1.6?
The mile was fixed at exactly 1609.344 metres in 1959. Rounding to 1.6 costs you nine metres per mile, which is a full 90 metres over a 10-mile route.
What is the quickest mental conversion between km and miles?
Multiply kilometres by 0.6 for a rough mile figure, or divide miles by 0.6 going the other way. It is about 3% off, which is fine for road signs and hopeless for engineering.
Does it handle very small measurements?
Yes, millimetres are included, which is the practical floor for tape measures and printing. Below that you are into microns, which this tool does not cover.
Worked example
A 5K in miles
Input: 5 kilometres → miles
Output: 3.107 miles
Note: That is why a 5K is often advertised as 'just over three miles' — the extra 0.107 mile is about 172 metres.