To convert inches to cm, multiply by 2.54: one inch is defined as exactly 2.54 centimeters. For example, 12 in = 30.48 cm, and 6.5 in = 16.51 cm.
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How to use the inches to cm converter
- Enter the length in inches, for example 9.75.
- Read the inches to cm converter result: 9.75 × 2.54 = 24.765 cm.
- For fractions, convert to decimals first: 3/8 in = 0.375 in = 0.9525 cm.
What is the inches to CM formula?
centimeters = inches × 2.54
The reverse is inches = centimeters × 0.39370079 (approximately).
The inch, foot, yard and mile are defined exactly in meters (1 in = 2.54 cm, 1 ft = 0.3048 m, 1 yd = 0.9144 m, 1 mi = 1,609.344 m), so these factors are exact.
What are inches and centimeters?
Length measures distance. The SI base unit is the meter. Since 1959 the international inch has been defined as exactly 2.54 cm, so the foot is exactly 0.3048 m and the mile exactly 1,609.344 m.
- Inch (in): 1 in = 0.0254 m (US/Imperial unit).
- Centimeter (cm): 1 cm = 0.01 m (Metric unit).
Inches to cm worked examples
- A 6-inch phone: 6 × 2.54 = 15.24 cm
- A 12-inch pizza: 12 × 2.54 = 30.48 cm
- A 65-inch TV (diagonal): 65 × 2.54 = 165.1 cm
Conversion chart
| in | cm | in | cm |
|---|---|---|---|
| 0.25 | 0.635 | 8 | 20.32 |
| 0.5 | 1.27 | 10 | 25.4 |
| 1 | 2.54 | 12 | 30.48 |
| 2 | 5.08 | 15 | 38.1 |
| 3 | 7.62 | 18 | 45.72 |
| 4 | 10.16 | 24 | 60.96 |
| 5 | 12.7 | 36 | 91.44 |
| 6 | 15.24 | 48 | 121.92 |
Values are rounded to four decimal places, or two for results of 100 or more.
Quick mental conversion
Multiply by 2.5 for a quick estimate (it understates by about 1.6%): 10 in ≈ 25 cm.
Fractions of an inch in millimeters and centimeters
| Inch fraction | Decimal inches | Millimeters | Centimeters |
|---|---|---|---|
| 1/16 | 0.0625 | 1.5875 | 0.15875 |
| 1/8 | 0.125 | 3.175 | 0.3175 |
| 1/4 | 0.25 | 6.35 | 0.635 |
| 3/8 | 0.375 | 9.525 | 0.9525 |
| 1/2 | 0.5 | 12.7 | 1.27 |
| 5/8 | 0.625 | 15.875 | 1.5875 |
| 3/4 | 0.75 | 19.05 | 1.905 |
| 7/8 | 0.875 | 22.225 | 2.2225 |
Screen sizes such as 65 inches measure the diagonal, not the width.
Inches from centimeters: reverse chart
Going the other way, inches = centimeters × 0.39370079. Common values:
| centimeters | inches |
|---|---|
| 1 | 0.3937008 |
| 2 | 0.7874016 |
| 5 | 1.968504 |
| 10 | 3.937008 |
| 20 | 7.874016 |
| 50 | 19.68504 |
| 100 | 39.37008 |
| 500 | 196.8504 |
| 1,000 | 393.7008 |
Screen sizes in centimeters
TV and monitor sizes are the diagonal in inches. In centimeters:
| Diagonal (in) | Diagonal (cm) |
|---|---|
| 13 | 33.02 |
| 15.6 | 39.62 |
| 24 | 60.96 |
| 27 | 68.58 |
| 32 | 81.28 |
| 43 | 109.22 |
| 55 | 139.7 |
| 65 | 165.1 |
| 75 | 190.5 |
A 16:9 screen’s width is about 0.872 times its diagonal, so a 55 in TV is about 121.8 cm wide.
Clothing measurements in cm
US jeans sizes give the waist and inseam in inches; European sizes often use centimeters. A 32 in waist is 81.28 cm, a 34 in waist 86.36 cm and a 30 in inseam 76.2 cm. Measure the body, not the label, because brands vary. Use the cm to inches converter for the reverse and the feet to cm converter for heights.
Pizza, bikes and rain
Pizza sizes are a good test of why area matters. A 12 inch pizza is 30.5 cm across. One 14 inch pizza has about 154 square inches of pizza, while two 10 inch pizzas have about 157, almost the same. Converting inches to cm does not change that comparison, but it helps when a menu abroad lists 30 cm and 35 cm sizes.
Bike wheels are named in inches, but the number is nominal. A “29 inch” mountain bike wheel uses the same 622 mm rim as a road bike’s 700c wheel; the tire makes up the rest. Tire sizes printed in ISO form (such as 57-622) are more reliable than the inch name.
Rainfall totals in US news come in inches. A storm dropping 1.5 inches of rain is 3.81 cm, or 38 mm, which is how most other countries report it.
Height and body measurements
Height in feet and inches needs one extra step: turn it into total inches first. 5 ft 6 in is 66 inches, which is 167.6 cm. Doctors’ offices outside the US record height in cm, and many online forms only accept metric values, so an inches to cm conversion is handy before filling them in. Round to the nearest whole centimeter; measuring height more precisely than that is not realistic at home.
Related converters and calculators
Related conversions:
- cm to inches: cm to in
- Inches to mm: in to mm
- Feet to cm: height
- Inches to feet: in to ft
- Length converter: all length units
Sources
NIST Special Publication 811, Appendix B; NIST: SI units – length.
Questions about this calculator
How many cm are in an inch?
2.54 cm exactly.
How do I convert inches to cm?
Multiply by 2.54. For example, 8 in = 20.32 cm.
What is 12 inches in cm?
30.48 cm.
How many cm is a 55 inch TV?
139.7 cm diagonally.
Is the inch defined exactly?
Yes: 1 in = 2.54 cm exactly since 1959.
Check the assumptions and units before relying on a result. Financial, tax and health estimates do not replace advice for your individual circumstances.
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