Unit Converter

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Unit Conversion – Quick Answers

Why is an inch exactly 2.54 cm?

The English inch equals the German “Zoll”. Since 1959 it’s defined as exactly 25.4 mm (2.54 cm). Use the inch-to-cm converter for screen sizes, tyres or woodworking.

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How accurate are the factors?

Length and weight conversions follow SI definitions; volume uses the US-gallon (3.78541 L). Results are rounded to two decimals.