12 inches to cm

How to convert 12 inches to cm

An inch is defined as exactly 2.54 centimeters, so multiply:

12 in × 2.54 = 30.48 cm

There is nothing to round: 30.48 cm is the exact value, and so is 304.8 mm. The converter above starts at 12 inches and also shows millimeters, meters and feet. For other lengths, use the full inches to cm converter; to go the other way, cm to inches.

12 inches, one foot and a 30 cm ruler

12 inches is one foot, so this page also answers “1 foot in cm”: 30.48 cm. A metric school ruler is usually 30 cm long, 4.8 mm short of a U.S. 12-inch ruler. Lay the two side by side and the marks drift apart as you go: at 6 inches the gap is 2.4 mm, at 12 inches 4.8 mm. That is why a part drawn as 12 inches and cut at 30 cm comes out about 3/16 in short.

When a pattern, a product listing or a school task says “12 inches (30 cm)”, the 30 cm is a rounded figure. Use 30.48 cm, or 305 mm, when the length must fit something exactly, such as a frame, a shelf or a pipe.

Nearby lengths

From 6 to 24 inches:

Each extra inch adds 2.54 cm, so the table is easy to extend in your head: 12 in is 30.48 cm, 13 in adds 2.54 to make 33.02 cm. For heights and lengths over a foot, written as feet and inches, see feet to cm.

Where 12 inches comes up

Pizzas, skillets and cake pans sold as 12 inches are 30.48 cm across; in metric shops the nearest size is 30 cm, close enough for any recipe. Floor and wall tiles sold as 12 × 12 inches measure 30.48 cm a side as a nominal size, and a 30 × 30 cm metric tile will not line up with them across a whole floor, since the 4.8 mm difference adds up tile after tile. Laptop and tablet screens are measured diagonally, so a 12-inch screen is 30.48 cm corner to corner, not along any side.