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Inches to Centimeters Converter
Convert inches to centimeters — and centimeters back to inches — instantly. Uses the exact factor of 2.54 cm per inch, the internationally defined standard since 1959.
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The Conversion Formula
Inches to Centimeters
cm = inches × 2.54
e.g. 12 × 2.54 = 30.48 cm
Centimeters to Inches
inches = cm ÷ 2.54
e.g. 30 ÷ 2.54 = 11.811 in
The factor 2.54 is exact by international definition — 1 inch = 2.54 cm precisely, established by the 1959 International Yard and Pound Agreement. It is the same standard used in manufacturing, science, and engineering worldwide.
Common Conversions
| Inches | Centimeters | Millimeters |
|---|---|---|
| 1 in | 2.54 | 25.4 |
| 2 in | 5.08 | 50.8 |
| 3 in | 7.62 | 76.2 |
| 4 in | 10.16 | 101.6 |
| 5 in | 12.70 | 127.0 |
| 6 in | 15.24 | 152.4 |
| 8 in | 20.32 | 203.2 |
| 10 in | 25.40 | 254.0 |
| 12 in | 30.48 | 304.8 |
| 18 in | 45.72 | 457.2 |
| 24 in | 60.96 | 609.6 |
| 36 in | 91.44 | 914.4 |
Unit Facts
- 1 inch = 2.54 cm = 25.4 mm = 0.0254 m
- 12 inches = 1 foot = 30.48 cm
- 1 cm = 10 mm = 0.3937 inches
- 1 meter = 100 cm = 39.3701 inches
Screen & Common Sizes
- 15.6 in (laptop)39.62 cm
- 27 in (monitor)68.58 cm
- 55 in (TV)139.70 cm
- 8.5 in (letter paper)21.59 cm
Frequently Asked Questions
How many centimeters is 1 inch?
1 inch = 2.54 centimeters exactly. This is the internationally defined value, established by the 1959 International Yard and Pound Agreement. It is exact — not an approximation.
How do I convert inches to centimeters?
Multiply the number of inches by 2.54. For example, 6 inches: 6 × 2.54 = 15.24 cm. To reverse (cm to inches), divide by 2.54.
What is 12 inches in centimeters?
12 inches is exactly 30.48 centimeters — the same as 1 foot. This is a useful anchor: every foot is 30.48 cm, and every inch is 2.54 cm.
How many inches is 1 centimeter?
1 centimeter = 0.393701 inches (1 ÷ 2.54). As a rough rule of thumb, 1 cm is slightly less than half an inch.
What is 6 inches in centimeters?
6 inches = 15.24 centimeters exactly (6 × 2.54). Six inches is exactly half a foot.
Is 2.54 exact or an approximation?
It is exact. One inch is defined as precisely 2.54 centimeters — a definition that has been in force since the 1959 International Yard and Pound Agreement. All conversions on this site use this exact constant.