Centimeters ⇄ Inches Converter

How to convert centimeters to inches

To convert centimeters to inches, divide the value by 2.54, or multiply it by about 0.393701.

in = cm ÷ 2.54

Example: 10 cm ÷ 2.54 = 3.93701 in

How to convert inches to centimeters

To convert inches to centimeters, multiply the value by 2.54.

cm = in × 2.54

Example: 10 in × 2.54 = 25.4 cm

1 cm = 0.393701 in · 1 in = 2.54 cm

Since 1959 the inch has been defined as exactly 2.54 centimeters, so these conversions are exact. Inches are used in everyday life mainly in the United States, and worldwide for screen sizes, wheels and pipes.

Where you meet centimeters and inches

The centimeter is one hundredth of a meter and the everyday unit of length in nearly every country: body measurements, furniture, paper and parcel sizes are given in centimeters or millimeters. The inch comes from the old English system, where it was one twelfth of a foot. Even if you think in centimeters, you will keep running into inches, because some products are sold by an inch size all over the world:

• Screens. TV, monitor, laptop and phone sizes are the length of the diagonal in inches.
• Jeans. A label such as W32 L34 means a 32-inch waist (81.3 cm) and a 34-inch inside leg (86.4 cm).
• Wheels. Car rims (17″, 18″) and many bicycle wheels are sized in inches.
• Paper and photos. US Letter paper is 8.5 × 11 in (21.59 × 27.94 cm), a little wider and shorter than A4 (21.0 × 29.7 cm, about 8.27 × 11.69 in). A classic 4 × 6 in photo print is 10.16 × 15.24 cm.

What screen sizes mean in centimeters

A “55-inch” TV measures 55 inches from corner to corner, which is 139.7 cm, but it is not 139.7 cm wide. On the usual 16:9 screen, the width is about 87% of the diagonal and the height about 49%. The table shows the visible picture; the frame adds a little more. To see the pixel size of your own display, open Screen Resolution.

Fractions of an inch

American tape measures, rulers and drill bits are marked in halves, quarters, eighths and sixteenths rather than decimals. In millimeters these are exact: 1/16 in = 1.5875 mm, 1/8 in = 3.175 mm, 1/4 in = 6.35 mm, 3/8 in = 9.525 mm, 1/2 in = 12.7 mm and 3/4 in = 19.05 mm. To go the other way, convert to decimal inches and find the nearest sixteenth: 10 cm is 3.937 in, and 0.937 × 16 ≈ 15, so 10 cm is almost exactly 3 15/16 in.

Quick mental math

• Centimeters to inches: multiply by 4 and divide by 10. 30 cm → 12 in (exact: 11.81 in). The answer comes out about 1.6% high.
• Inches to centimeters: multiply by 2.5, then add 2%. 32 in × 2.5 = 80, plus 1.6 = 81.6 cm (exact: 81.28 cm). Without the last step you are about 1.6% short.

Common mistakes

• Mixing up the marks. ″ (or ") means inches and ′ (or ') means feet: 6′ is six feet, 6″ is six inches.
• Taking nominal sizes literally. Some inch sizes are names, not measurements. A US “2 × 4” board is actually about 1.5 × 3.5 in (38 × 89 mm), and pipe sizes don’t match the pipe’s real diameter either.

FAQ

How big is a 15.6-inch laptop screen in centimeters?

The diagonal is 39.6 cm, and a 16:9 picture is about 34.5 × 19.4 cm. The laptop itself is a few centimeters wider because of the frame.

How many pixels do I need to print a 4 × 6 inch photo?

At the common print quality of 300 pixels per inch, you need 1200 × 1800 pixels. You can scale a photo to that size with the Image Resizer.

Are shoe sizes in inches?

Not directly. US, UK and European shoe sizes are separate numbering systems, so a size 9 is not 9 inches. Some countries, such as Japan and Korea, label shoes by foot length in centimeters or millimeters, which is the easiest to compare with a measurement of your own foot.

How many inches are in one meter?

One meter is 100 cm, or about 39.37 inches, a little more than a US yard (36 in).

Need another unit? The Unit Converter converts length, weight, temperature, area, volume, speed, time, data, pressure and energy.