Example 1
- Direction: inches to cm
- 1 in
2.54 cm
How many cm is 1 inch? 2.54 cm, because an inch is exactly 2.54 cm.
Inches to cm
The calculator converts inches to centimeters. One inch is exactly 2.54 cm. Twelve inches are 30.48 cm, not a round 30. The result stays in centimeters, without feet.
The other page, cm to inches, is on cm to inches. Thread and sheet metal: inches to mm.
Result
Enter a length in inches or in centimeters. The result will appear here.
How it works
The calculator multiplies inches by 2.54. 1 inch is 2.54 cm. 12 inches are 30.48 cm. A 15.6 in screen diagonal is 39.624 cm.
The other way, you divide centimeters by 2.54. 180 cm of height is 70.8661 in.
The international inch has been exactly 25.4 mm, or 2.54 cm, since 1959. The 2.5 cm shortcut is too loose for frames and height.
The result is one number in centimeters or in inches. The calculator does not write the result as feet and inches, such as 5 ft 11.
You may enter zero; the result is then also zero. The calculator does not accept negative numbers.
A comma and a period give the same fraction. A US letter at 8.5 in is 21.59 cm.
Formula
cm = in × 2.54; in = cm / 2.54
The international inch is exactly 2.54 cm. That is the 1959 definition, not a rounding.
How to use
- Choose inches to centimetres.
- Enter 1. The result is 2.54 cm.
- Enter 12. The result is 30.48 cm.
- The other way, enter 180. The result is 70.8661 in.
1 inch is 2.54 cm
The international inch is 2.54 cm. 12 inches are 30.48 cm.
- in
- International inch. 1 in = 2.54 cm. The result is not split into feet.
- cm
- Centimeter. 12 in = 30.48 cm. A 15.6 in screen is 39.624 cm.
- 2.54
- The 1959 inch constant. Not the 2.5 shortcut.
Examples
Example 2
- Direction: inches to cm
- 12 in
30.48 cm
How many cm are 12 inches? 30.48 cm, not a round 30.
Example 3
- Direction: inches to cm
- 15.6 in
39.624 cm
How many cm is a 15.6 in diagonal? 39.624 cm.
Related calculators
Frequently asked questions
How many cm is 1 inch?
Exactly 2.54 cm. The 2.5 cm shortcut is too loose for frames and height.
How many cm are 12 inches?
30.48 cm. A 30 cm school ruler is not a foot.
How many cm is a 15.6 in screen?
39.624 cm. That is the diagonal, not the case width.
Is the result in feet and inches?
No. The result is one number in centimetres or in inches. 5 ft 11 belongs on the cm-to-feet-and-inches page.
Is a tailor inch different?
Not on this page. The factor is 2.54 cm from 1959.
Can length be negative?
No. Zero is allowed; after conversion the result is still zero.
How is this different from inches to mm?
Same constant, different scale. Thread and sheet metal use millimetres. Height and waist usually use cm.
How many cm is 67 in?
170.18 cm. A US letter at 8.5 in is 21.59 cm.
Do a comma and a period both work?
Yes. 15,6 and 15.6 give the same fraction.
Where do I convert cm to inches?
On the cm to inches page. That page starts from centimeters.
Sources
The international inch is 2.54 cm.
Page updated in 2026.