The cm to inches conversion factor
One inch equals exactly 2.54 centimeters, so to convert centimeters to inches you divide by 2.54: inches = cm ÷ 2.54. For example, 30 cm ÷ 2.54 = 11.81 inches. To go the other way, use the inches to cm calculator.
The 2.54 figure is exact rather than rounded: since 1959 the international inch has been defined as exactly 25.4 mm, which fixes an inch at 2.54 cm by definition. Cm-to-inch conversions therefore never lose accuracy — any error comes purely from how you round the answer.
The same numbers feed straight into the feet to inches calculator.
How to convert centimeters to inches
Enter your length in centimeters and the calculator divides it by 2.54 to give inches. This works for height, screen sizes, fabric, and any measurement. Round the result to two decimal places for everyday use.
Two measuring traps are worth knowing. Screen and TV sizes are diagonals, so a 55-inch TV measures 139.7 cm corner to corner, not across the front. Fabric and lumber are usually quoted in eighths of an inch, so convert first and then round: 20 cm is 7.87 in, which in practice is 7 7/8 in.
Worth having open at the same time: the centimeters to meters calculator.
CM to inches reference table
| Centimeters | Inches |
|---|---|
| 1 cm | 0.39 in |
| 10 cm | 3.94 in |
| 30 cm | 11.81 in |
| 100 cm | 39.37 in |
Height reference points: 150 cm is 59.06 in (4 ft 11 in), 165 cm is 64.96 in (5 ft 5 in), 180 cm is 70.87 in (5 ft 10.9 in) and 190 cm is 74.80 in (6 ft 2.8 in).
Keep the meters to feet calculator nearby for the rest of the same job.
Frequently asked questions
- How many inches is 30 cm?
- 30 cm equals 11.81 inches (30 ÷ 2.54).
- What is the cm to inches formula?
- inches = centimeters ÷ 2.54, because 1 inch is exactly 2.54 cm.
- How many cm are in one inch?
- Exactly 2.54 centimeters are in one inch.
- How do I convert inches back to cm?
- Multiply inches by 2.54, or use the inches to cm calculator.
- How do I write 175 cm as feet and inches?
- Divide by 2.54 to get 68.90 inches, then divide by 12: that is 5 whole feet with 8.90 inches left over, so 175 cm is 5 ft 8.9 in. Rounding the inches before splitting off the feet is what makes people lose the last half inch.