What this calculator does
Converting inch to cms is one of the most searched unit conversions there is, because rulers, tape measures, screen sizes and furniture dimensions switch between imperial and metric depending on the country and the product.
The relationship is exact and fixed: one inch equals precisely 2.54 centimetres, a figure set by international agreement in 1959 and used without exception since. Enter a value, pick the direction, and both the centimetre and millimetre equivalents come out together.
The formula
To convert inches to cms, multiply by 2.54. To convert centimetres to inches, divide by 2.54. Because the factor is exact rather than a rounded approximation, the conversion is precise at any scale, from a small component measurement up to a room dimension.
| Term | Meaning |
|---|---|
| Inch | An imperial and US customary unit of length, exactly 2.54 centimetres. |
| Centimetre | A metric unit of length equal to one hundredth of a metre. |
| Conversion factor | The fixed, exact ratio between the two units: 1 inch = 2.54 cm. |
The inputs explained
| Field | What to enter |
|---|---|
| Value | The value to convert. |
| Convert | Choose whether to convert inches to centimetres, or centimetres to inches. |
When to use it
Checking a screen or device size
Screen sizes are almost always quoted in inches even in metric countries, so converting inches to cms is a common check before comparing it against a metric measurement of the available space.
Reading a US furniture or clothing size
US retailers frequently list dimensions in inches; converting to centimetres makes those figures directly comparable to a metric tape measure or floor plan.
Converting a small measurement precisely
Because 2.54 is an exact factor rather than a rounded one, this conversion holds its precision even for small components or fine tolerances, unlike some approximate unit conversions.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
Inches to cms, at common lengths
A range of inch values, each converted to centimetres.
| Inches | Centimetres | In millimetres |
|---|---|---|
| 1 | 2.540 | 25.40 mm |
| 6 | 15.240 | 152.40 mm |
| 12 | 30.480 | 304.80 mm |
| 24 | 60.960 | 609.60 mm |
| 36 | 91.440 | 914.40 mm |
| 60 | 152.400 | 1,524.00 mm |
Centimetres to inches, at common lengths
A range of centimetre values, each converted to inches.
| Centimetres | Inches | In millimetres |
|---|---|---|
| 10 | 3.937 | 100.00 mm |
| 25 | 9.843 | 250.00 mm |
| 50 | 19.685 | 500.00 mm |
| 100 | 39.370 | 1,000.00 mm |
| 150 | 59.055 | 1,500.00 mm |
| 200 | 78.740 | 2,000.00 mm |
Questions
How many cm is an inch?
Exactly 2.54 cm. This has been the internationally agreed, exact definition of the inch since 1959, so the figure is not a rounded approximation.
How do I convert inches to cms?
Multiply the number of inches by 2.54. For example, 5 inches × 2.54 = 12.7 cm.
How do I convert cm to inches?
Divide the number of centimetres by 2.54. For example, 25 cm ÷ 2.54 ≈ 9.84 inches.
Why is the inch defined as exactly 2.54 cm?
Before 1959, the inch varied slightly between the US, UK and Canada. The International Yard and Pound Agreement of that year fixed the inch at exactly 2.54 cm everywhere, removing the small discrepancies between national standards.
For the full metric and imperial length ladder, millimetres up to miles and nautical miles, see the length converter. For height and weight together, see the height & weight converter.