Source unit
Inch in
An inch is a length unit used in US customary and Imperial measurement.
One inch equals exactly 25.4 millimeters.
Inch to Centimeter Converter
Reverse conversion: Centimeter to InchResult
Inch to Centimeter
Exact11 in==2.542.54 cm
How to convert inches to centimeters
Formula, method and accuracy
1 inch equals 2.54 centimeters.
Multiply the inch value by exactly 2.54. The unit definition introduces no approximation; any rounding should reflect the source measurement and the needs of the receiving specification.
cm = in × 2.54
1 in × 2.54 = 2.54 cm
- Operation
- Multiply by factor
- Method
- Linear
- Accuracy
- Exact ratio
Conversion table
Practical and common reference values
| Inches (in) | Centimeters (cm) |
|---|---|
| ¼ (0.25) | 0.6350.635 |
| ½ (0.5) | 1.271.27 |
| ¾ (0.75) | 1.9051.905 |
| 11 | 2.542.54 |
| 1½ (1.5) | 3.813.81 |
| 22 | 5.085.08 |
| 3½ (3.5) | 8.898.89 |
| 1212 | 30.4830.48 |
| 2424 | 60.9660.96 |
About Inches and Centimeters
Inches are imperial and US customary length units; centimeters are metric length units. This direction uses the exact factor 2.54.
Inch as the source, Centimeter as the result
Use this direction when an original dimension is stated in inches and a metric document, product listing, drawing, or comparison requires centimeters. The measurement is preserved while its notation changes from imperial or US customary units to metric units.
Result unit
Centimeter cm
Centimeter is a unit used to measure length.
One centimeter equals 0.01 meters.
Where inch-to-centimeter conversion is useful
This direction is useful for imported product sizes, screen diagonals, construction dimensions, tools and fittings, and specifications that must be compared with metric measurements.
Exact relationship and decimal representation
One international inch equals exactly 2.54 centimeters. The one-unit result is a finite decimal, but a sensible converted value should still reflect the precision of the original inch measurement.
Check fractional-inch inputs
A fractional measurement such as 3 1/2 inches represents 3.5 inches, not 3.12 inches. Convert the fraction correctly before applying the exact 2.54 factor, and do not imply more measurement precision than the source provides.
How this conversion is verified
The international inch is defined as exactly 25.4 millimeters, which makes one inch exactly 2.54 centimeters. The converter uses that definition for the live result and every table row; display rounding is kept separate from the underlying value.
Standards used for this conversion
- NIST: SI Units – LengthThe international inch definition and its exact 25.4 millimeter relationship.
- NIST: Guide for the Use of the International System of UnitsSI usage and authoritative conversion-factor guidance.
- NIST: Writing with SI (Metric System) UnitsRounding and significant-digit guidance for converted measurements.
For a quick estimate, multiply inches by 2.5 and add a small correction. For an exact conversion, use 2.54 rather than the estimate.
An inch-to-centimeter conversion applies to linear dimensions. Square inches and cubic inches belong to area and volume and use different factors.
Frequently asked questions
6 answers for this conversion
- How do I convert inches to centimeters?
- Multiply the inch value by exactly 2.54. For example, 8 inches × 2.54 equals 20.32 centimeters.
- How many centimeters are in one inch?
- One international inch equals exactly 2.54 centimeters.
- How do I convert fractional inches to centimeters?
- First express the fraction as an inch value, then multiply by exactly 2.54. For example, one half inch is 0.5 inch, so it equals 1.27 centimeters.
- Does the 2.54 factor apply to every international inch?
- Yes. The international inch is defined as exactly 2.54 centimeters. Historical inch definitions may differ, so identify the source standard when working with archival measurements.
- How many centimeters is 3½ inches?
- Three and one-half inches is 3.5 inches. Multiplying 3.5 by 2.54 gives exactly 8.89 centimeters.
- Should an inch-to-centimeter result always show two decimals?
- No. The factor 2.54 is exact, but the appropriate displayed precision depends on the source measurement and the receiving specification. Do not add precision the original measurement did not provide.
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