Inches to CM Converter
Convert inches to centimeters in one step. Enter a length in inches and get the exact value in cm, with the formula, examples and common sizes below.
Centimeters = Inches × 2.54
Inches to CM Formula
To convert inches to centimeters, multiply the number of inches by 2.54. The factor is exact, not a rounded approximation, so the only rounding in the answer is the number of decimals you choose to display. To go the other way, divide centimeters by 2.54.
Inches and Centimeters Explained
The inch (in) is a traditional unit of length that is still the everyday standard for screens, paper, tools, tyres and body measurements in the United States, and it remains common in the United Kingdom and Canada for some uses. Since the international agreement of 1959, one inch has been fixed at exactly 2.54 centimeters, so it no longer depends on any old body-based or grain-based definition.
The centimeter (cm) is one hundredth of a meter and is part of the metric (SI) system used in almost every other country. Because the metric system works in tens, moving from centimeters to millimeters or meters only means shifting a decimal point.
How to Convert Inches to Centimeters
- Type the length in inches into the input box. Decimals such as 8.5 work, and negative values are accepted for offsets and signed measurements.
- The answer in centimeters appears at once, or press Convert Now.
- Use Swap Units to convert centimeters to inches, Copy Result to copy the answer, or Clear to start again.
Step-by-step by hand
- Write down the length in inches, for example 15 in.
- Multiply by 2.54: 15 × 2.54 = 38.1.
- Add the unit: 15 in = 38.1 cm.
For a quick mental estimate, multiply by 2.5 (double the number and add half of the original). The result is about 1.6% low, which is fine for rough sizing. Fractions of an inch work the same way: convert the fraction to a decimal first, so 3/8 in = 0.375 in = 0.9525 cm.
Practical Examples
- TV screen: a 55-inch diagonal is 55 × 2.54 = 139.7 cm.
- US letter paper: 8.5 × 11 in is 21.59 × 27.94 cm.
- Waist size: a 32-inch waist is 81.28 cm.
- Laptop screen: a 15.6 in display measures 39.624 cm across the diagonal.
- Fraction: 1/2 in = 0.5 in = 1.27 cm.
- Negative value: −3 in = -7.62 cm, useful for an offset measured to the left of or below a reference line.
Inches to CM – Common Values
Quick reference for frequently used conversions
| Inches (in) | Centimeters (cm) | Millimeters (mm) |
|---|---|---|
| 1/8 in | 0.3175 cm | 3.175 mm |
| 1/4 in | 0.635 cm | 6.35 mm |
| 1/2 in | 1.27 cm | 12.7 mm |
| 3/4 in | 1.905 cm | 19.05 mm |
| 1 in | 2.54 cm | 25.4 mm |
| 2 in | 5.08 cm | 50.8 mm |
| 3 in | 7.62 cm | 76.2 mm |
| 4 in | 10.16 cm | 101.6 mm |
| 5 in | 12.7 cm | 127 mm |
| 6 in | 15.24 cm | 152.4 mm |
| 8 in | 20.32 cm | 203.2 mm |
| 10 in | 25.4 cm | 254 mm |
| 12 in | 30.48 cm | 304.8 mm |
| 15 in | 38.1 cm | 381 mm |
| 20 in | 50.8 cm | 508 mm |
| 24 in | 60.96 cm | 609.6 mm |
| 30 in | 76.2 cm | 762 mm |
| 36 in | 91.44 cm | 914.4 mm |
| 48 in | 121.92 cm | 1,219.2 mm |
| 60 in | 152.4 cm | 1,524 mm |
| 72 in | 182.88 cm | 1,828.8 mm |
Where and Why This Conversion Is Used
Whenever a product, plan or piece of advice crosses between imperial and metric countries, inches have to be turned into centimeters.
- Shopping online: TV and monitor sizes, picture frames, bag dimensions and furniture are often listed in inches on international sites.
- Clothing and tailoring: waist, inseam and chest measurements are quoted in inches in the US and in centimeters in much of the world.
- Printing and design: paper, banner and photo sizes are commonly given in inches even when the rest of the job is metric.
- DIY and building: imported tools, hardware and fittings are sized in inches, while your tape measure or plans may be in centimeters.
- Shipping and travel: airline cabin-bag limits and parcel dimensions are stated in either unit.
For smaller or larger units, see the Inches to MM Converter and the Feet to CM Converter.