inches to cm formula
To convert inches to centimeters, multiply the number of inches by 2.54. In symbols: cm = in × 2.54.
One inch equals 2.54 centimeters, and one centimeter equals 0.393700787402 inches. An inch is exactly 25.4 millimeters, so the factor 2.54 cm per inch is exact and carries no rounding.
Worked example
Suppose you have 12 inches and need the answer in centimeters.
- Write the formula: cm = in × 2.54.
- Put in the number: 12 × 2.54 = 30.48.
- Round to suit the job. 30.48 cm is accurate enough for most everyday uses.
So 12 in is 30.48 cm. To check, convert back: 30.48 cm is 12 in.
Common inches to centimeters values
| inches (in) | centimeters (cm) |
|---|---|
| 1 | 2.54 |
| 2 | 5.08 |
| 5 | 12.7 |
| 10 | 25.4 |
| 20 | 50.8 |
| 50 | 127 |
| 100 | 254 |
Reference points
Some familiar amounts in inches, converted to centimeters:
- 1 in, one inch: 2.54 cm
- 6 in, a typical smartphone height: 15.24 cm
- 27 in, a common monitor size: 68.58 cm
- 72 in, six feet: 182.88 cm
Where you will use it
Screen sizes, tire widths, furniture dimensions and sewing patterns are often in inches, while rulers and shipping boxes outside the US use centimeters. Tailors convert chest and waist sizes this way.
Quick mental math
Multiply by 2.5 and add a little: 12 in gives 30, and the exact value is 30.48 cm. Rule of thumb: multiply by 2.5. For 12 in this gives 30 cm against the exact 30.48, an error of 1.6 percent.
Going the other way
Need the reverse? Use the cm to inches converter. For comparison, 1 cm is 0.39370079 in. To compare every length unit at once, open the length converter.
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