About the CM to Inches
This CM to inches converter changes centimeters into inches using the exact international definition, 1 inch = 2.54 cm. Along with the decimal answer it shows the nearest fraction of an inch (to 1/16″) — the way tape measures and rulers are marked in the US — and the length in feet and inches for longer measurements.
Use it for screen and monitor sizes, clothing measurements such as waist or inseam, paper and photo sizes, furniture dimensions, or any product listing that gives sizes in centimeters when you think in inches. The reference chart lists common values from 1 cm to 100 cm.
Because the factor is exact, the only rounding is in the digits displayed. The fraction output is rounded to the nearest sixteenth, which is the finest mark on most imperial tape measures.
With the default inputs, the inches is 11.811 in. Change any value above to recalculate instantly.
How to use the cm to inches
- 1Type the measurement in centimeters.
- 2Read the decimal inches, or the nearest 1/16″ fraction for a tape measure.
- 3Use the feet-and-inches result for longer lengths.
- 4Check the chart for other common conversions.
Formula and method
The international inch is defined as exactly 2.54 centimeters, so dividing a centimeter measurement by 2.54 gives inches with no approximation. Equivalently, multiply by 0.393701 (1 ÷ 2.54, rounded).
For a tape-measure reading the decimal is rounded to the nearest 1/16 inch and reduced (8/16 becomes 1/2). Feet are inches ÷ 12, and millimeters are simply centimeters × 10.
- cm
- Length in centimeters
- 2.54
- Centimeters in one inch (exact)
Worked examples
30 cm ruler
30 ÷ 2.54 = 11.81 inches, just under a foot. To the nearest sixteenth that is 11 13/16 inches (11.8125).
One meter
100 ÷ 2.54 = 39.37 inches, which is 3 feet (36 in) plus 3.37 in. A meter is a little over a yard.
15 cm phone
15 ÷ 2.54 = 5.906 inches. 0.9055 × 16 ≈ 14.49, which rounds to 14/16 = 7/8, giving 5 7/8 inches.
Frequently asked questions
How many inches is 1 cm?+
One centimeter is 0.3937 inches (1 ÷ 2.54). Put the other way, one inch is exactly 2.54 centimeters.
How do I convert cm to inches quickly?+
Divide by 2.54. For a rough mental estimate, multiply by 4 and divide by 10 — 50 cm × 0.4 = 20 in, versus the exact 19.69 in.
How many inches is 30 cm?+
30 cm is 11.81 inches, a little under one foot. A standard 30 cm school ruler is therefore about 11 13/16 inches long.
Is 2.54 an exact conversion factor?+
Yes. Since the 1959 international yard and pound agreement, the inch has been defined as exactly 25.4 mm, so 2.54 cm per inch is exact.