Unit conversion guide
Centimetres to Inches Guide
How to convert centimetres to inches, when to round, and why cm-to-inch conversion matters for sizing and product measurements.
Updated 16 October 2026 • Reviewed by Tools by Layna Editorial Team • General information only
Centimetres to inches is one of the most useful everyday length conversions. It appears in height, clothing measurements, monitors, furniture, product listings, packaging, craft projects and imported size charts.
The formula
To convert centimetres to inches, divide centimetres by 2.54. To convert inches back to centimetres, multiply inches by 2.54. The 2.54 relationship is exact for the international inch.
Example
A 30 cm item is 11.81 inches. A 180 cm height is 70.87 inches, which is 5 feet 10.87 inches if you split the result into feet and remaining inches.
Sizing context
For product sizing, keep one decimal place or two decimal places depending on the use. A rough home measurement can be rounded. A tight fit should not be rounded until the end.
Common mistake
Do not use 2.5 unless the result is only a rough mental estimate. It is close, but it can drift enough to matter across larger measurements.
Height conversions
Height is often written in feet and inches rather than total inches. Convert cm to total inches first, divide by 12 for feet, then keep the remainder as inches.
Best calculator path
Use the length converter when you need cm, mm, metres, inches, feet, yards and miles in one place.
Exact factor, sizing and measurement error
One inch is defined as exactly 2.54 centimetres. Divide centimetres by 2.54 to get inches; multiply inches by 2.54 to get centimetres. Because the factor is exact, most uncertainty comes from the original measurement and the rounding used for the final answer.
Clothing and product sizing are not guaranteed by a correct conversion. A garment labelled with centimetres may use body measurements, flat garment measurements or a size-chart range. Compare the same measurement type and read the brand’s instructions before selecting a size.
Height is often written in feet and inches rather than decimal feet. A result of 70.5 inches is 5 feet 10.5 inches because 60 inches make five feet. It is not 5 feet 0.5 inches. Keep the total inches until the final feet-and-inches split.
For construction or manufacturing, measure with equipment suited to the required tolerance. Converting a rough tape measurement to many decimal places does not create extra accuracy; the displayed precision should reflect the source measurement.
A practical display rule is to keep one decimal place for body or furniture measurements unless the source was measured more precisely. For manufacturing tolerances, follow the drawing specification. Showing hundredths of an inch from a rough centimetre measurement creates false precision rather than better information.
Sources and review notes
- National Measurement Institute — Australia’s National Measurement Institute maintains Australia’s measurement system and primary measurement standards. Use official measurement standards where legal, trade or technical precision matters.