Convert Centimeter to Inch
Conversion Formula
in = cm × 0.393701To convert Centimeter to Inch, use the formula above. This is the standard conversion factor used worldwide.
Conversion Table
| Centimeter (cm) | Inch (in) |
|---|---|
| 1 | 0.393701 |
| 10 | 3.937010 |
| 100 | 39.370100 |
| 1000 | 393.701000 |
Why convert Centimeter to Inch
Height is the conversion people run most often here, translating a centimeter figure from a birth certificate, a European ID, or a fitness app into the feet-and-inches format US forms and dating profiles expect. Furniture, luggage, and appliance listings from overseas retailers give dimensions in centimeters too, and you need the inch equivalent before you know if a wardrobe clears a doorway or a suitcase meets a carry-on limit.
Where the number comes from
The inch has been fixed at exactly 2.54 centimeters since 1959, when the US, UK, Canada, Australia, South Africa, and New Zealand signed the international yard and pound agreement that aligned their previously slightly different national inches into one value. That makes this conversion exact rather than approximate: multiplying by 2.54 introduces no rounding error, unlike most metric-to-imperial pairs that carry a repeating decimal.
Quick reference
| 1 cm | 0.3937 in | |
| 1 in | 2.54 cm | exact, by definition |
| 30 cm | 11.81 in | |
| 100 cm | 39.37 in | just under 3 ft 3 in |
| 170 cm | 5 ft 6.9 in | a common adult height |
| 55 cm | 21.65 in | a typical airline carry-on length limit |
Common mistakes
- Rounding the factor to 2.5 for speed is common and feels harmless, but it understates every result by about 1.6 percent, which adds up to more than a centimeter of error on an adult height.
- Another frequent mistake is converting only the inch part of a feet-and-inches height, treating 5'9" as if it were 9 inches, instead of converting the full figure in inches first.
Frequently Asked Questions
Why is 2.54 the exact conversion and not a rounded figure?
Before 1959 the US and British inches were defined slightly differently and differed by a few parts per million. The international yard and pound agreement fixed the inch at exactly 2.54 cm across all six signatory countries, replacing several near-identical national definitions with one exact value.
How do I convert a height like 175 cm into feet and inches?
Divide 175 by 2.54 to get total inches (68.9). Divide that by 12 to get whole feet (5), and the remainder is the leftover inches (8.9), which rounds to 5 ft 9 in.
Was the US inch always exactly 2.54 cm?
No. Before 1959 the US inch was defined through the US survey foot and was marginally longer than the international inch now in use, by about two parts per million, a gap that is irrelevant outside of land surveying, where the old US survey foot is still occasionally referenced.
Does this conversion work the same for area, in square inches or square centimeters?
No, you square the linear factor rather than reusing it directly. One square inch equals 2.54 squared, or 6.4516 square centimeters, not 2.54.