How to convert cm to in
in = cm × 0.3937007874. The scale factor is the source-unit factor divided by the destination-unit factor.
Worked example
A component measured at 30 cm converts to 11.81102362 in.
- Start with 30 cm.
- Multiply 30 by 0.3937007874.
- Report 11.81102362 in, rounded to the precision of your original measurement.
The calculator returns decimal inches. A ruler marked in fractional inches may require a separate rounding step to the nearest marked fraction.
Check the reverse conversion
1 in = 2.54 cm. Use the inch to centimeter converter to calculate in the opposite direction. This has its own formula and reference table.
Definitions that matter
An international inch is exactly 2.54 cm and a foot is exactly 0.3048 m. These tools do not use historical US survey feet. For square measurements, use the area category instead.
The base unit for this category is m. One cm corresponds to 0.01 m; one in corresponds to 0.0254 m. These definitions explain the relationship rather than relying on a rounded display value.
Sources and precision
Definitions: NIST Guide to the SI. Calculations use double precision; the tool defaults to a readable rounded result, while tables show up to ten significant digits. Displaying more digits does not increase the accuracy of the original measurement.
Read our calculation methodology and content standards, or continue with length definitions and common conversions.