Inches to Centimeters

Inches and centimeters are the bread and butter of design, engineering, and daily household measurements. The inch is the primary unit of length in the Imperial system, while the centimeter is the metric standard. Since 1959, the international inch has been defined as exactly 25.4 millimeters (or 2.54 centimeters). This exactness is what allows global manufacturing supply chains to function, ensuring a bolt made in inches fits a nut designed in centimeters.

Screen sizes are always measured diagonally in inches — a convention that has never converted to metric. A 6.7-inch smartphone display is 17.02 cm. A 15.6-inch laptop is 39.62 cm. A 27-inch monitor is 68.58 cm. A 65-inch TV is 165.1 cm — almost as wide as a door. Knowing the cm equivalent helps you understand the actual physical size when shopping from international retailers or comparing specs across brands.

Paper and print sizes cross this boundary constantly. US Letter (8.5 × 11 inches) is 21.59 × 27.94 cm, slightly different from A4 (21 × 29.7 cm) — a mismatch that causes layout problems when printing US-formatted documents on European printers. Standard photo print sizes like 4×6 inches = 10.16 × 15.24 cm and 5×7 inches = 12.7 × 17.78 cm are needed when ordering prints internationally.

Clothing and shoe sizing is another area where inches and centimeters collide. Waist measurements for US jeans are in inches (32W = 81.28 cm). Bra band sizes in the US are inches, while European sizing uses centimeters. Shoe sizes in the US use a proprietary scale, but international size charts always give the foot length in centimeters. For tailoring, woodworking, or any trade craft, converting between these systems accurately prevents expensive material waste and rework.