Inches to Centimeters Converter

How many centimeters are in an inch?

One inch equals exactly 2.54 centimeters. This is not a measured approximation: the figure is fixed by definition. In 1959 the national standards bodies of the United States, the United Kingdom, Canada, Australia, New Zealand and South Africa agreed to define the international yard as 0.9144 meters, and the inch (one thirty-sixth of a yard) follows as 25.4 millimeters.

centimeters = inches × 2.54Going the other way, divide: inches = centimeters ÷ 2.54.

Because the factor is exact, any rounding you see comes from how many digits are displayed, never from the conversion itself. This converter shows up to four decimal places.

Inches and centimeters compared

The inch belongs to the imperial and US customary systems, where twelve inches make a foot. The centimeter is a metric unit: one hundredth of a meter. Neither is better, but they dominate different places. Screen sizes, tire widths and plumbing fittings are still quoted in inches in many countries, while body measurements, furniture catalogs and school rulers in most of the world use centimeters.

Paper is a handy reference. US Letter is 8.5 × 11 inches, which is 21.59 × 27.94 cm. The international A4 sheet is 21 × 29.7 cm, or about 8.2677 × 11.6929 inches. Two sheets that look almost identical are different by a few millimeters, and this converter makes the gap visible.

How to convert inches to centimeters

1. Type the length in inches into the first box. Decimals are fine, so enter a fraction such as 5 1/2 as 5.5.
2. Read the length in centimeters in the second box. It updates as you type, and you can also press the convert button.
3. To go back from centimeters to inches, divide by 2.54 or use the centimeters to inches converter.

Example 1. A monitor advertised as 27 inches measures 27 × 2.54 = 68.58 cm across its diagonal.

Example 2. Someone who is 5 ft 9 in tall is 5 × 12 + 9 = 69 inches, and 69 × 2.54 = 175.26 cm. Always change feet into inches first (or use the inches to feet converter in reverse).

Example 3. A 15 cm ruler is 15 ÷ 2.54 = 5.9055 inches, a little under six.

Inches to centimeters conversion table

Quick estimates and common mistakes

For a mental estimate, multiply by 2.5 and add a little: 10 inches is about 25 cm, and the exact answer of 25.4 is only 1.6% higher. Multiplying by 2.5 is easy to do in your head: double the number, then add half of the original.

• Mixing up the direction. Centimeters are smaller than inches, so the number in centimeters is always larger. If your answer is smaller than the input, you divided instead of multiplying.
• Reading fractions as decimals. 5 1/2 inches is 5.5, not 5.12. Convert the fraction first.
• Forgetting feet. A height given as 6 ft 2 in is 74 inches before you multiply by 2.54.
• Rounding too early. Keep the full value through a chain of calculations and round only the final result.