Inches to Centimeters Converter
1 inch (in) equals 2.54 centimeters (cm).
Quick answer
To convert inches to centimeters, multiply by 2.54. The factor is exact: 1 inch = 2.54 cm by definition, so 12 inches (1 foot) = 30.48 cm.
- 1 inch = 2.54 centimeters
- 1 centimeter = 0.3937007874 inches
- Formula: cm = in × 2.54
- Quick estimate: multiply by 2.5 and add a bit: 20 in × 2.5 = 50, exact 50.8 cm.
1 inch = 2.54 centimeters
How to convert inches to centimeters
cm = in × 2.54
To convert inches to centimeters, multiply the number of inches by 2.54.
Example: 42 in to cm
- Start with the value in inches: 42 in.
- Multiply by 2.54: 42 × 2.54 = 106.68.
- Result: 42 inches = 106.68 centimeters.
Going the other way, 1 centimeter = 0.393700787402 inches, so to convert centimeters back to inches you divide by the same number. See centimeters to inches.
Where the conversion factor comes from
Since the international yard and pound agreement of 1959, the inch has been defined as exactly 2.54 centimeters. Before that, the US and the UK used slightly different inches (the US inch was 2.540005 cm). The 1959 definition made the conversion exact, so 2.54 is not a rounded number: every inch-to-centimeter conversion is a multiplication by exactly 2.54.
Mental math: in to cm in your head
Multiply by 2.5 (halve the number and multiply by 5, or multiply by 10 and divide by 4), then add about 1.6% more. For example, 14 inches: 14 × 10 = 140, ÷ 4 = 35, plus a little = 35.6 cm (exact: 35.56).
Anchors worth remembering: 1 inch ≈ 2.5 cm, 4 inches ≈ 10 cm and 1 foot ≈ 30 cm.
When you need to convert inches to centimeters
- Understanding TV, monitor, phone and laptop sizes, which are sold by their diagonal in inches everywhere in the world.
- Converting US recipes and baking pan sizes (a 9 × 13 inch pan is about 23 × 33 cm).
- Bike wheel and tire sizes, pipe and fitting sizes, and US tools.
- Converting height given in feet and inches to centimeters.
Common mistakes
- Converting the width of a TV using its size: a 55-inch TV is 55 inches diagonally (140 cm), not wide.
- Dividing instead of multiplying: there are more centimeters than inches for the same length.
- Mixing up inches (″) and feet (′) in written measurements.
Everyday inches in centimeters
| Example | Inches | Centimeters |
|---|---|---|
| Smartphone screen (diagonal) | 6.1 in | 15.494 cm |
| Standard pizza (medium) | 12 in | 30.48 cm |
| Laptop screen (diagonal) | 15.6 in | 39.624 cm |
| Computer monitor (diagonal) | 27 in | 68.58 cm |
| Living room TV (diagonal) | 55 in | 139.7 cm |
| Bicycle wheel (road) | 28 in | 71.12 cm |
Converting a height? The height converter works in feet and inches directly, for example 5′7″ in cm or 170 cm in feet.
Inches to centimeters conversion table
| Inches (in) | Centimeters (cm) |
|---|---|
| 0.1 in | 0.254 cm |
| 0.2 in | 0.508 cm |
| 0.3 in | 0.762 cm |
| 0.4 in | 1.016 cm |
| 0.5 in | 1.27 cm |
| 0.6 in | 1.524 cm |
| 0.7 in | 1.778 cm |
| 0.8 in | 2.032 cm |
| 0.9 in | 2.286 cm |
| 1 in | 2.54 cm |
| 1.5 in | 3.81 cm |
| 2 in | 5.08 cm |
| 2.5 in | 6.35 cm |
| 3 in | 7.62 cm |
| 3.5 in | 8.89 cm |
| 4 in | 10.16 cm |
| 4.5 in | 11.43 cm |
| 5 in | 12.7 cm |
| 6 in | 15.24 cm |
| 7 in | 17.78 cm |
| 7.5 in | 19.05 cm |
| 8 in | 20.32 cm |
| 9 in | 22.86 cm |
| 10 in | 25.4 cm |
| 11 in | 27.94 cm |
| 12 in | 30.48 cm |
| 13 in | 33.02 cm |
| 14 in | 35.56 cm |
| 15 in | 38.1 cm |
| 16 in | 40.64 cm |
| 17 in | 43.18 cm |
| 18 in | 45.72 cm |
| 19 in | 48.26 cm |
| 20 in | 50.8 cm |
| 21 in | 53.34 cm |
| 22 in | 55.88 cm |
| 23 in | 58.42 cm |
| 24 in | 60.96 cm |
| 25 in | 63.5 cm |
| 26 in | 66.04 cm |
More in to cm values
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What is an inch?
The inch is a unit of length in the imperial and US customary systems equal to exactly 2.54 centimeters.
What is a centimeter?
The centimeter (also spelled centimetre) is a metric unit of length equal to one hundredth of a meter.
Convert inches to other units
Convert other units to centimeters
Frequently asked questions
How many centimeters are in an inch?
One inch is 2.54 centimeters.
How many inches are in a centimeter?
One centimeter is 0.3937007874 inches.
What is the formula to convert inches to centimeters?
cm = in × 2.54.
How many cm is a 55-inch TV?
A 55-inch TV measures 139.7 cm diagonally. A 16:9 screen of that size is about 121.8 cm wide and 68.5 cm tall.
How do I convert feet and inches to cm?
Convert the feet to inches (× 12), add the inches, then multiply by 2.54. For example, 5 ft 9 in = 69 in = 175.26 cm.