Convert Inch to Centimeter (in → cm)

Converting inches to centimeters is straightforward: multiply by the conversion factor. Follow these three steps to do it by hand or in your head.

1. 1
   Take your value in inches

   Start with the number of inches (in) you want to convert.
2. 2
   Multiply by 2.54

   The conversion factor from in to cm is 2.54. Multiply your value by this number.
3. 3
   Read the result in centimeters

   The result is your value in centimeters (cm).

Multiply the value in inches by 2.54. For the reverse direction, multiply by 0.393701.

• ✓1 inch = 2.54 cm exactly by international agreement — no rounding.
• ✓Screen sizes are always diagonal, never width. A 27-inch monitor is about 60 cm wide.
• ✓To convert cm to inches mentally, divide by 2.5 and subtract 1.6%.

• ✗Reading a screen size as width. A 65-inch TV is about 143 cm wide — the 165 cm figure is diagonal.
• ✗Using 2.5 instead of 2.54 on precision drawings — the 1.6% error matters in manufacturing.
• ✗Confusing inches of length with inches of mercury (inHg) — a pressure unit, not length.

What is the Inch?

The inch equals exactly 25.4 millimeters under the 1959 international yard and pound agreement. The word derives from the Old English 'ynce,' from Latin 'uncia' meaning one twelfth (the inch is one twelfth of a foot). Originally based on the width of a thumb, the inch has been standardized for centuries. It is the global standard for screen sizes (a 15-inch laptop or 65-inch TV), pipe and tubing diameters (1-inch plumbing, 2-inch exhaust), and shoe sizes in Anglo-Saxon countries. Construction lumber, photographic prints, paper sizes (US Letter is 8.5 × 11 in), and rainfall in the US all use inches. The inch relates to the millimeter (25.4 mm = 1 in exactly), the foot (12 in = 1 ft), and the yard (36 in = 1 yd). Subdivisions in fractions (½, ¼, ⅛) remain common in carpentry.

• Screen and monitor diagonals worldwide (phone, tablet, TV)
• US and UK shoe sizes
• Industrial pipe and fitting diameters

What is the Centimeter?

The centimeter equals one hundredth of a meter (0.01 m) and is the everyday metric unit for body measurements, clothing, furniture, and household items. It bridges the gap between the meter (too large for personal items) and the millimeter (too small for clothing). The centimeter is widely used in countries with metric systems for height (a person is 160–185 cm tall), paper sizes (A4 is 21 × 29.7 cm), and medical measurements. Although not strictly an SI base unit, it is one of the most common units in daily metric usage. The centimeter relates to the inch (1 cm ≈ 0.394 in) and to the millimeter (1 cm = 10 mm). It became standard with the metric system's adoption across continental Europe in the 19th century.

• Height and body measurements in medical records
• Ready-to-wear clothing sizes in Europe and Asia
• Furniture and interior design dimensions