How to Convert Centimetres to Inches (cm to in)
Length conversions come up when reading overseas furniture specs, cycling the Round Island Route in kilometres while a foreign app shows miles, or checking marine distances in the Singapore Strait in nautical miles. This guide shows how to convert centimetres into inches by hand, with examples and a quick-reference table.
The conversion
To convert centimetres to inches, multiply the value by 0.3937007874. To go the other way, divide by the same number (or multiply by 2.54). For a quick estimate, multiply by about 0.39.
Inches = centimetres × 0.3937007874
Worked examples
- 3 cm = 1.1811 in
- 12.5 cm = 4.9213 in
- 75 cm = 29.5276 in
Centimetres to Inches table
| Centimetres | Inches |
|---|---|
| 1 cm | 0.393701 in |
| 2 cm | 0.787402 in |
| 5 cm | 1.9685 in |
| 10 cm | 3.937 in |
| 20 cm | 7.874 in |
| 25 cm | 9.8425 in |
| 50 cm | 19.685 in |
| 100 cm | 39.3701 in |
| 250 cm | 98.4252 in |
| 500 cm | 196.8504 in |
| 1,000 cm | 393.7008 in |
Common questions
Is cm to in exact?
The factors used here are the internationally defined values where they exist; results are rounded for display only.
How do I convert back?
Use the Inches to Centimetres converter.
Mistakes to avoid
Rounding the factor too early
Using 3 instead of 3.28 for feet per metre introduces an error of almost 9% before you have started.
Mixing similar-sounding units
US and imperial gallons, pints and tons are different sizes, and decimal kilobytes differ from binary kibibytes.
Dropping the units
A bare number without a unit is easy to misread later. Always write the unit with the result.
Background
Many conversion factors are exact by definition. The inch has been defined as exactly 2.54 centimetres since 1959, and the pound as exactly 0.45359237 kilograms, so conversions involving them can be as precise as you need.
For everyday use, three or four significant figures are usually enough. Engineering, science and trade documents may need more, and rounding should happen only at the end of a calculation.
Singapore adopted the metric system in the 1970s, replacing imperial units and traditional Chinese measures in most official uses. Metric units are now standard in schools, trade and government, but older units survive in property, markets and imported goods.
For any value, use the Centimetres to Inches Converter or browse all length converters.
Run your own numbers: Centimetres to Inches Converter