Inches to Centimeters Converter

Converting inches to centimetres is the most common length conversion there is, and it rests on an unusually clean fact: since 1959 the international inch has been defined as exactly 2.54 centimetres. This is not a measured approximation that improves with better instruments — it is a definition agreed by the countries maintaining the imperial system, chosen so that the inch and the metric system line up precisely. Every inch-to-centimetre conversion is therefore exact, and any answer you see is limited only by how many decimal places are displayed.

The arithmetic is a single multiplication: multiply the number of inches by 2.54 to get centimetres. Twelve inches, one foot, is 30.48 cm. A 32-inch television is 81.28 cm across the diagonal. Because the factor is exact, you can also work backwards precisely by dividing by 2.54, which is what the reverse field on this page does.

The reason this conversion comes up so often is that the United States, and to a lesser extent the United Kingdom and Canada, still express many everyday measurements in inches while the rest of the world uses centimetres. Screen sizes, wheel diameters, paper dimensions, clothing measurements, lumber, plumbing fittings, and body measurements all cross that boundary regularly. The conversion table on this page is deliberately built around those real reference points rather than a plain arithmetic sequence, so you can scan for the size you actually care about — common screen diagonals, ruler markings, and construction dimensions — instead of converting one value at a time.

One practical caution: in trades that still work in inches, sizes are often nominal rather than actual. A piece of lumber sold as two-by-four inches measures closer to 1.5 by 3.5 inches once dressed, and a half-inch pipe refers to an approximate internal bore rather than any exact external dimension. Converting a nominal size to centimetres gives you an arithmetically correct number for a dimension the object does not physically have. When precision matters, measure the object rather than converting its label.