Convert Inch to Centimeter
Convert inches to centimeters instantly. 1 inch = 2.54 centimeter — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Centimeter to Inch converter for the reverse conversion.
Units explained
Inch
An inch is an Imperial and US customary unit of length defined since 1959 as exactly 25.4 millimeters (0.0254 meters). It is still the standard small unit of length in the United States, the United Kingdom (informally), and a few other countries.
The inch derives from the Roman uncia (one-twelfth of a foot) and survived through Anglo-Saxon and medieval English measurement systems. Various definitions persisted regionally until the 1959 International Yard and Pound Agreement standardized the inch globally as exactly 25.4 mm.
Inches are used in the US and UK for body height, screen sizes (TVs, monitors, phones), tire sizes, plumbing, lumber, paper sizes (US Letter is 8.5 × 11 in), and most consumer product specifications in the United States.
Anglo-Saxon origin (predating 1066); standardized to 25.4 mm exactly by the International Yard and Pound Agreement of 1959, signed by the US, UK, Canada, Australia, New Zealand, and South Africa.
Centimeter
A centimeter is a metric unit of length equal to one hundredth of a meter (1/100 m). It is one of the most commonly used SI sub-units in daily life, especially for measuring small objects, body dimensions, paper sizes, and short distances.
The centimeter emerged from the French metric system established by the French Academy of Sciences in 1793. The metric system introduced decimal-based prefixes (milli-, centi-, deci-, deca-, hecto-, kilo-) to create proportional sub-units of the meter.
Centimeters are the standard unit for everyday measurement in nearly every country outside the United States. They are used for body height, clothing sizes, rainfall, paper formats (A4 is 21 × 29.7 cm), screen dimensions, and most consumer product specifications.
Developed in France during the late 18th century as part of the metric system designed by the French Academy of Sciences. Formally adopted in France in 1795 and ratified internationally through the Metre Convention signed in Paris in 1875.
Inch to Centimeter conversion formula
The relationship between inches and centimeters:
To convert inches to centimeters, multiply the value in inches by 2.54. To reverse, multiply centimeters by 0.3937007874.
How to use this converter
Type a value into the calculator. The result in centimeters updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Centimeter to Inch converter for the reverse direction.
Step-by-step: convert inches to centimeters
- Write down the value in inches (in).
- Multiply that value by the factor 2.54.
- The product is the equivalent value in centimeters (cm).
- To reverse, multiply the centimeter value by 0.3937007874.
Worked examples
Example 1 — Convert 1 in to cm:
1 × 2.54 = 2.54 cm
Example 2 — Convert 100 in to cm:
100 × 2.54 = 254 cm
Real-world example — US Letter paper width
US Letter paper is 8.5 inches wide, which is 21.59 cm. International printers convert this every time they accept a US-format PDF, because their paper trays are calibrated in metric A4 (21.0 cm) and the half-centimeter difference matters.
8.5 in × 2.54 = 21.59 cm
Real-world example — Translating US ruler markings to metric
A standard 12-inch ruler equals exactly 30.48 cm. Schoolchildren learning the metric system often re-derive that two adjacent inch marks span 2.54 cm — converting from inches to centimeters is the first hands-on metric conversion most US students learn.
12 in × 2.54 = 30.48 cm
Real-world example — TV diagonal screen sizes
A 55-inch TV has a screen diagonal of about 139.7 cm. International retailers list TVs in inches (diagonal) but European wall-mount kits spec the bracket separation in centimeters. Converting inches to cm is part of every furniture-and-electronics planning calculation.
55 in × 2.54 = 139.7 cm
Inch to Centimeter conversion table
Standard reference values for converting inches to centimeters:
| Inch [in] | Centimeter [cm] |
|---|---|
| 0.01 | 0.0254 |
| 0.1 | 0.254 |
| 1 | 2.54 |
| 2 | 5.08 |
| 3 | 7.62 |
| 4 | 10.16 |
| 5 | 12.7 |
| 10 | 25.4 |
| 20 | 50.8 |
| 30 | 76.2 |
| 40 | 101.6 |
| 50 | 127 |
| 100 | 254 |
| 500 | 1270 |
| 1000 | 2540 |
Frequently asked questions
How many centimeters is 1 inch?
How do I convert inches to centimeters?
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How many centimeters is 100 inches?
Popular length unit conversions
Convert Inch to other length units
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Metric / SI (18 units)
Imperial / US Customary (26 units)
Nautical (1 units)
Astronomical (9 units)
Atomic / Physics (6 units)
Typographic (3 units)
Sources & references
Conversion factor (1 in = 2.54 cm) verified against the following authoritative sources:
- BIPM — The International System of Units (SI Brochure 9th ed.)
Official BIPM publication defining the seven SI base units (including the meter) and the rules for their use. The global authority on units of measurement.
- NIST — Guide to the SI
US National Institute of Standards and Technology reference covering the SI base and derived units with definitions and usage rules for US technical practice.
- NIST Special Publication 811 — Guide for the Use of the International System of Units
Detailed NIST guide covering exact conversion factors between SI and US customary units along with formatting and rounding conventions.
- NIST — Refinement of values for the yard and pound (Federal Register 1959)
The treaty (signed by US
- International Astronomical Union — System of Astronomical Constants
The IAU defines astronomical units including the AU (149597870700 m exactly) light-year and parsec used in astronomy and astrophysics.