Conversion · General Conversion
Formula verified
cm to inches Converter
Enter a length and pick a direction — the conversion updates as you type, using the exact centimeter-to-inch factor.
Direction
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Inches
70.866
180 cm = 70.866 in
Step-by-step proofCheck by hand
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The exact conversion
An inch is internationally defined as exactly 2.54 centimeters, so dividing a centimeter figure by that number gives inches, and multiplying an inch figure by it gives centimeters back. This is the single most-searched length conversion, and unlike the pound-kilogram factor, it's exact and easy enough to do in your head as a rough check: roughly 2.5 centimeters to the inch.
The formula
in = cm ÷ 2.54 · cm = in × 2.54
Worked example
180 cm ÷ 2.54 ≈ 70.866 in.
Frequently asked questions
How many inches are in a centimeter?
One centimeter equals exactly 0.3937007874 inches, because an inch is internationally defined as exactly 2.54 centimeters. Everyday conversions usually round this to 0.3937 inches per centimeter, which is accurate enough for most purposes but not exact.
Why is the inch defined in terms of the centimeter?
Since 1959, the international inch has been defined as exactly 2.54 centimeters by international agreement, rather than the centimeter being defined from the inch. That makes the centimeter (and the meter it derives from) the base unit and the inch a fixed multiple of it, which is why this converter's math goes from inches to centimeters and back through that one exact number.
Sources and method
- Centimeter–inch conversion factor — internationally defined exact equivalence (NIST Handbook 44).