📏 Inches to CM Converter, Convert Inches to Centimeters
By Shihab Mia · Updated 2026-07-12
To convert inches to centimeters, multiply the number of inches by 2.54; for example, 12 inches x 2.54 = 30.48 cm. This works because one inch is defined as exactly 2.54 centimeters, so the factor never changes. Type in either field below and the other updates instantly, so you can also go from cm back to inches by dividing by 2.54.
What is the inches to cm Converter?
The inch and the centimeter come from two different measuring systems. The inch is part of the imperial and US customary systems still used in the United States, the United Kingdom, and a few other places, while the centimeter is part of the metric system used almost everywhere else. For a long time the inch was defined in slightly different ways in different countries, which caused small but annoying discrepancies in engineering and trade.
That was fixed in 1959, when the international yard and pound agreement set the inch to exactly 2.54 centimeters. Because this is a definition and not a measurement, the factor is exact: there is no rounding hidden inside it. So the conversion is simply cm = inches x 2.54. A 6 inch phone screen is 6 x 2.54 = 15.24 cm, and a 36 inch curtain drop is 36 x 2.54 = 91.44 cm.
To go the other way, from centimeters to inches, you divide by the same factor: inches = cm / 2.54. So 30 cm is 30 / 2.54 = 11.811 inches. Because 1 cm is only about 0.3937 of an inch, centimeter values are always a larger number than the equivalent inch value, which is a quick sanity check that you multiplied and divided the right way round.
Precision matters most when small errors add up. Cutting fabric, sizing a picture frame, or machining a part can go wrong if you round 2.54 down to 2.5 early in a calculation, because that 1.6 percent error scales with every inch. Keep the full factor of 2.54 until the very last step, then round the final answer to the precision your task actually needs.
When to use it
- Converting a TV, monitor, or phone screen size given in inches into centimeters for a wall space or bag.
- Working out clothing and body measurements when a size chart mixes inches and centimeters.
- Reading US furniture, curtain, or appliance dimensions and checking they fit a metric room plan.
- Doing school or engineering homework where a length must be expressed in the metric system.
How to use the inches to cm Converter
- Type the length in inches into the Inches field (it starts at 12 as an example).
- Read the centimeter result, which updates instantly as you type.
- To convert the other way, type a value into the Centimetres field to get inches.
- Use the preset buttons for common sizes, or press Clear to start over.
Formula & method
Worked examples
Convert a 12 inch length to centimeters.
- Start with the value in inches: 12.
- Multiply by the exact factor 2.54: 12 x 2.54.
- Work out the product: 12 x 2.54 = 30.48.
Result: 12 in = 30.48 cm
Convert 50 cm back into inches.
- Start with the value in centimeters: 50.
- Divide by the exact factor 2.54: 50 / 2.54.
- Work out the quotient: 50 / 2.54 = 19.685.
- Round to a sensible precision, here three decimals.
Result: 50 cm = 19.685 in
Inches to centimeters conversion chart (exact, factor 2.54)
| Inches | Centimeters |
|---|---|
| 1 in | 2.54 cm |
| 2 in | 5.08 cm |
| 3 in | 7.62 cm |
| 5 in | 12.7 cm |
| 6 in | 15.24 cm |
| 10 in | 25.4 cm |
| 12 in | 30.48 cm |
| 24 in | 60.96 cm |
| 36 in | 91.44 cm |
| 60 in | 152.4 cm |
Centimeters to inches chart (reverse, divide by 2.54)
| Centimeters | Inches |
|---|---|
| 1 cm | 0.3937 in |
| 5 cm | 1.9685 in |
| 10 cm | 3.937 in |
| 20 cm | 7.874 in |
| 30 cm | 11.811 in |
| 50 cm | 19.685 in |
| 100 cm | 39.37 in |
Common mistakes to avoid
- Rounding the factor to 2.5 too early. The exact factor is 2.54, not 2.5. Using 2.5 introduces a 1.6 percent error that grows with the length: a 36 inch value comes out as 90 cm instead of the correct 91.44 cm. Keep 2.54 in the sum until the final step.
- Confusing the two directions. To get centimeters you multiply by 2.54; to get inches you divide by 2.54. Multiplying when you meant to divide turns 10 cm into 25.4 inches instead of the correct 3.937 inches. The cm value is always the bigger number.
- Mixing up centimeters and millimeters. There are 10 millimeters in a centimeter. 1 inch is 2.54 cm but 25.4 mm. Reading a metric ruler in the wrong unit gives an answer that is out by a factor of 10.
- Treating feet and inches as one number. A height like 5 feet 9 inches is not 5.9 inches. Convert it to inches first (5 x 12 + 9 = 69 in), then multiply by 2.54 to get 175.26 cm.
Glossary
- Inch
- A unit of length in the imperial and US customary systems, defined as exactly 2.54 centimeters since 1959.
- Centimeter
- A metric unit of length equal to one hundredth of a meter. Ten millimeters make one centimeter.
- Conversion factor
- The fixed number you multiply or divide by to move between units. For inches and centimeters it is exactly 2.54.
- Imperial system
- A system of units including inches, feet, and yards, still common in the US and UK.
- Metric system
- The decimal measuring system based on meters, centimeters, and millimeters used across most of the world.
- Exact value
- A number defined without rounding. Because 1 inch is defined as 2.54 cm, the factor carries no measurement error.
Frequently asked questions
How do I convert inches to cm?
Multiply the number of inches by 2.54. For example, 10 inches x 2.54 = 25.4 cm. One inch equals exactly 2.54 centimeters, so this single factor works for any length.
How many cm are in an inch?
There are exactly 2.54 centimeters in one inch. This has been the international definition since 1959, so it is an exact value rather than a rounded approximation.
What is 12 inches in cm?
12 inches is 30.48 cm. You multiply 12 by 2.54 to get 30.48. Twelve inches is also one foot, so one foot equals 30.48 cm.
How do I convert cm back to inches?
Divide the number of centimeters by 2.54. For example, 30 cm / 2.54 = 11.811 inches. Type a value into the Centimetres field above and the tool does this for you.
Is 1 inch exactly 2.54 cm?
Yes. Under the 1959 international yard and pound agreement, one inch is defined as exactly 2.54 centimeters, so there is no rounding hidden in the factor.
What is 5 feet 9 inches in cm?
First turn it into inches: 5 x 12 + 9 = 69 inches. Then multiply by 2.54: 69 x 2.54 = 175.26 cm. So 5 feet 9 inches is about 175.3 cm.