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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.

in
2.54
cm
Decimals:
Exact 2.54 cm/in Live as-you-type No signup

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 in2.5425.4
2 in5.0850.8
3 in7.6276.2
4 in10.16101.6
5 in12.70127.0
6 in15.24152.4
8 in20.32203.2
10 in25.40254.0
12 in30.48304.8
18 in45.72457.2
24 in60.96609.6
36 in91.44914.4

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.