Convert Inch to Centimeter

The inch-to-centimeter direction is the one you reach for when an American spec sheet lands on a metric workshop floor. One inch is exactly 2.54 cm — that figure has been the legal definition since 1959, so there is no rounding involved, only multiplication. A standard 1/2-inch bolt shank is precisely 1.27 cm; a 4-inch PVC pipe has an outside diameter of exactly 10.16 cm.

Clothing is another daily flashpoint. US and Canadian sizing lists chest, waist and inseam in inches, while European and Asian brands use centimeters. Multiply the inch figure by 2.54 to land on the right shelf. A 32-inch inseam, for instance, is 81.28 cm — close enough to an 81 cm European size but worth knowing the exact number before ordering internationally.

Watch out when reading fractional inches off a ruler. An eighth of an inch (0.125 in) is 0.3175 cm, and sixteenths get smaller still. Decimal-inch and fractional-inch readings look similar but can be millimeters apart after conversion — always confirm whether a measurement is, say, 3.5 in (8.89 cm) or 3½ in (the same thing) versus 3 5/16 in (8.415 cm).