Centimeter to Inch Converter
Converts centimeter to inch (cm to in) and back. The conversion factor is shown below every result.
How to Convert Centimeter to Inch
What Is a Centimeter?
A centimeter (cm) is an SI unit of length equal to one hundredth of a meter.
What Is an Inch?
An inch (in) is a US customary and imperial unit of length, defined as exactly 25.4 millimeters.
Common Centimeter to Inch Reference Points
Real-world reference values for quick sanity checks.
| Item | Centimeter (cm) | Inch (approx.) |
|---|---|---|
| A US letter sheet width | 21.59 cm | 8.5 in |
| A standard sheet of paper (A4) width | 21 cm | 8.27 in |
| Average smartphone height | 15 cm | 5.91 in |
| 1 foot | 30.48 cm | 12 in |
| Reference values are illustrative approximations for common items, not measured specifications. | ||
Centimeter to Inch Conversion Table
| Centimeter (cm) | Inch (in) |
|---|---|
| 1 cm | 0.393701 in |
| 2 cm | 0.787402 in |
| 3 cm | 1.181102 in |
| 5 cm | 1.968504 in |
| 10 cm | 3.937008 in |
| 20 cm | 7.874016 in |
| 30 cm | 11.811024 in |
| 50 cm | 19.685039 in |
| 100 cm | 39.370079 in |
| 150 cm | 59.055118 in |
| 200 cm | 78.740157 in |
| Source: NIST SP 811, Appendix B (1959 International Yard and Pound Agreement: 1 in = 2.54 cm exactly) | |
Frequently Asked Questions
How do I convert centimeters to inches?
Multiply the centimeter value by 0.3937007874. For example, 15 cm × 0.3937007874 = 5.905511811 in. The reverse conversion multiplies inches by 2.54 to get centimeters.
Why is 2.54 the conversion number for inches to centimeters?
1 inch was defined as exactly 2.54 centimeters under the 1959 International Yard and Pound Agreement, which standardized the inch, foot, and yard against the meter for English-speaking countries. It's an exact definition, not a rounded approximation.
Is this converter accurate enough for sewing or woodworking?
Yes. The underlying factor (0.3937007874015748) is exact to the precision shown. For fine woodworking or sewing, round to the precision your tools can actually measure. Most tape measures and rulers read to 1/16 in or 1 mm, so extra decimal places beyond that don't add real-world accuracy.
What's the difference between an international inch and a US survey inch?
The international inch (2.54 cm exactly) is what's used almost everywhere today, including on this page. The US survey inch is a very slightly different, older definition still used in some historical US land surveying records; the difference is about 2 parts per million and irrelevant for everyday conversions.
Related Length Converters
A good measuring tool marked in both cm and in removes the guesswork at the point of use.