Length Converter
Convert between metric and imperial length units, from millimeters to miles.
1 mm =
0.1 cm
How to use
- Type the value to convert — decimals are fine.
- Pick the current unit on the left and the target unit on the right. The middle button swaps direction.
- The result updates as you type. Check the conversion table and formula below, too.
Frequently asked questions
How accurate are the results?+
Calculations use the internationally standardized (SI) definitions; only the display is rounded to about six significant digits. That's plenty for everyday, school and work use.
How many cm is an inch, exactly?+
By international agreement (1959), 1 inch = exactly 2.54 cm. It's a definition, not an approximation.
How do I express height in feet and inches?+
Convert cm to feet, then multiply the decimal part by 12 to get inches. Example: 175 cm = 5.74 ft = 5 ft 8.9 in.
Does it need a fast connection?+
No. The math runs instantly inside your browser with no server round-trip — it even works offline once the page is open.
Is it really free?+
Yes. No sign-up, no install, no usage limits. The site is ad-supported.
Unit guide
Metric vs imperial
Most of the world measures in meters, while the US (and partly the UK) lives in inches, feet, yards and miles. Clothing sizes, monitor and tire specs (inches), golf and aviation distances (yards, miles) — that's where the two systems collide and conversion is needed.
A few anchors make estimates fast: 1 inch ≈ 2.5 cm (a thumb joint), 1 foot ≈ 30 cm, 1 mile ≈ 1.6 km, 1 yard ≈ 0.9 m (one big step).
How this converter calculates
Every unit is converted to meters first, then divided into the target unit. The inch (2.54 cm), foot (30.48 cm) and mile (1,609.344 m) are all exact defined values, so there is no rounding error in the math.