Convert Inches (in) to Centimeters (cm)
Inches to centimeters is one of the few imperial–metric conversions with an exact factor: 1 inch = 2.54 cm, fixed by international agreement in 1959. Screens, paper sizes and clothing mix the two units daily.
Formula
1 in = 2.54 cm
To convert in to cm, multiply the value by 2.54.
Conversion Table
| Inches (in) | Centimeters (cm) |
|---|---|
| 0.01 in | 0.0254 cm |
| 0.1 in | 0.254 cm |
| 0.5 in | 1.27 cm |
| 1 in | 2.54 cm |
| 2 in | 5.08 cm |
| 3 in | 7.62 cm |
| 5 in | 12.7 cm |
| 10 in | 25.4 cm |
| 15 in | 38.1 cm |
| 20 in | 50.8 cm |
| 25 in | 63.5 cm |
| 50 in | 127 cm |
| 100 in | 254 cm |
| 250 in | 635 cm |
| 500 in | 1270 cm |
| 1000 in | 2540 cm |
| 2500 in | 6350 cm |
| 5000 in | 12700 cm |
| 10000 in | 25400 cm |
| 50000 in | 127000 cm |
Common in to cm Examples
- 1 in = 2.54 cm
- 5 in = 12.7 cm
- 10 in = 25.4 cm
- 25 in = 63.5 cm
- 50 in = 127 cm
- 100 in = 254 cm
- 500 in = 1270 cm
- 1000 in = 2540 cm
About in to cm
The 2.54 cm inch is a definition, not an approximation — since the 1959 international yard and pound agreement, the inch has been defined through the metric system. That is why "about 2.5" works for quick estimates: multiply inches by 2.5, then add 2% if you need precision.
The pair shows up constantly in screen sizes, which are quoted as diagonals in inches worldwide: a 6.1-inch phone is 15.5 cm, a 15.6-inch laptop is 39.6 cm, and a 55-inch TV is about 140 cm across the diagonal. US letter paper (8.5 × 11 in) is 21.6 × 27.9 cm — slightly wider and shorter than A4.
Frequently Asked Questions
Why is an inch exactly 2.54 cm?
Because the inch is defined that way: the 1959 international yard and pound agreement fixed the yard at 0.9144 m, which makes 1 inch exactly 2.54 cm by definition.
How long is a 6.5-inch phone screen in cm?
About 16.5 cm measured diagonally — screen sizes are always the diagonal, not the height or width.
What is the difference between in and cm?
Both measure Length, but they belong to different unit systems or scales, which is why a conversion factor is needed between them.
Why are there different units for Length?
Different regions and industries developed their own Length standards over time. International trade and science later required conversion tools to bridge them.
How many decimal places should I keep when converting in to cm?
For everyday use, 2 to 4 decimal places are enough. Scientific or engineering work may require 6 or more.
Can I convert cm back to in?
Yes. Simply invert the ratio: divide the cm value by 2.54 to get the equivalent in in.
How do I convert in to cm by hand?
Take the value in in and multiply the value by 2.54. The result is the same value expressed in cm.
Is the conversion from in to cm exact?
The ratio 2.54 is defined to high precision and is exact for most practical purposes. Rounding only matters when many decimal places are needed.