CM to Inches Converter

1. Keep Direction on Centimeters to inches and type the length in cm, such as a waist of 81 or a height of 170.
2. Pick the inch fraction you want to read. Use 1/16 in for a tape measure, or 1/2 in for clothing labels.
3. Read the decimal inches and the nearest fraction. The panel also shows feet and inches for anything over 12 in.

What each line of the result tells you:

One centimeter is 0.393700787 in, a little under 4/10 of an inch. Put the other way, one inch is exactly 2.54 cm.

The centimeter is one hundredth of a meter, the SI base unit of length. NIST lists centi as one of 24 SI prefixes, which run from quecto (10 to the power -30) to quetta (10 to the power 30) since four were added in 2022.

The inch is a US customary and imperial unit. A 1959 notice by the US National Bureau of Standards fixed the inch at exactly 25.4 mm, which is 2.54 cm. The same notice says the American Standards Association had already adopted 25.4 mm for industrial use in 1933. UK law gives the same value, since it defines the inch as 1/36 of a yard of 0.9144 m.

Most of the world measures bodies, furniture and fabric in cm, while US and many UK buyers still think in inches. For very small parts such as drill bits and bolts, the mm to inches converter is the better fit.

The tool divides centimeters by 2.54 to get decimal inches, then rounds those inches to the fraction you picked.

1. Divide by 2.54. For a 76 cm inseam, 76 / 2.54 = 29.9213 in.
2. Multiply by the fraction size and round to a whole number. At 1/16 in: 29.9213 x 16 = 478.74, which rounds to 479.
3. Divide back: 479 / 16 = 29 15/16 in. That fraction is 0.41 mm longer than the true length.
4. For a label, round again. Most jeans makers would call this a 30 in inseam, which is 76.2 cm.

NIST SP 811 lists inch to centimeter as 2.54 E+00, an exact factor. Dividing by 2.54 is therefore exact. The multiplier 0.3937 is a rounded version and is off by 2 parts per million.

Height of 170 cm. 170 / 2.54 = 66.9291 in. Take out 5 ft (60 in) and 6.9291 in is left, which is 5 ft 6 15/16 in at 1/16 in.

Waist of 81 cm. 81 / 2.54 = 31.8898 in, or 31 7/8 in. A size-32 waist is 81.28 cm, so this measurement sits 2.8 mm under it.

Screen of 140 cm. Many shops outside the US list screen size in cm. 140 / 2.54 = 55.1181 in. A screen sold as 55 in is 139.7 cm, and the size always means the diagonal, not the width.

Chest of 96 cm. 96 / 2.54 = 37.7953 in, or 37 13/16 in, which a shirt chart would round to 38 in.

A4 paper. The short side of 21 cm is 8.2677 in, about 8 1/4 in, so it is slightly narrower than US Letter at 8 1/2 in. For print jobs, the print size calculator links pixel counts to inch sizes.

The factor 2.54 never changes. Your result changes with the fraction size, the way you measure and how a maker rounds its labels.

Fraction Size

A 1/16 in fraction is never more than 0.79 mm off. A 1/4 in fraction can be 3.18 mm off, and 1/2 in can be 6.35 mm off. For 170 cm, 1/16 in gives 66 15/16 in, but 1/4 in gives 67 in.

How You Measure a Body

A soft tape pulled tight or held loose can change a waist reading by 1 to 2 cm, which is up to 3/4 in. Measure over light clothing, keep the tape level, and repeat once.

Nominal Sizes

Clothing sizes and screen sizes are labels. A 32 in waist label does not promise 81.28 cm of fabric, and a screen label is often rounded to a whole inch. Check the chart for the brand you are buying.

Measuring Precision

A reading to the nearest centimeter carries up to 5 mm of doubt, which is about 3/16 in. Showing that reading to 1/32 in does not make it more accurate.

An inch is 2.54 times longer than a centimeter. Centimeters count in tens, while inches split into halves, quarters, eighths and sixteenths.

A 30 cm ruler is 11.811 in, so it is 0.48 cm shorter than a 12 in ruler. That gap is why the two sides of a dual ruler never line up past the first few marks.

Body Measurements and Size Charts

Sewing patterns, fitness trackers and many online stores list waist, hip, chest and inseam in cm. Convert each one before you pick a US size. Heights also need feet, and the centimeters to feet converter handles decimal feet and rounding for forms.

Screens, Monitors and Frames

A monitor listed as 68.6 cm is a 27 in screen, since 27 x 2.54 = 68.58 cm. Picture frames and posters sold in cm, such as 50 x 70 cm, are 19 11/16 x 27 9/16 in.

Clothing and Fabric

An EU pattern may ask for 90 cm of fabric width, which is 35 7/16 in. To go back from inch sizes to cm, use the inches to cm converter, which is built for that direction.

Each value below uses the exact 2.54 factor. The fraction columns round to the nearest 1/8 and 1/16 in.

Note that 2.5 cm is 0.9843 in, just under 1 in. Treating 2.5 cm as an inch loses 0.4 mm each time, which adds up to 1.6 mm over four inches.

1. Multiplying by 2.54 Instead of Dividing

Going from cm to inches needs division. Multiplying 81 cm by 2.54 gives 205.7, which is the wrong unit and the wrong size.

2. Using 2.5 as the Factor

Dividing by 2.5 gives answers 1.6 percent too high. For a 170 cm height that is 68 in instead of 66.93 in, an extra inch.

3. Reading Decimal Inches as Fractions

31.89 in is not 31 and 89/100 on a tape marked in sixteenths. It is closest to 31 7/8 in.

4. Treating a Screen Size as Its Width

A 140 cm screen is 140 cm across the diagonal. Its width is smaller and depends on the aspect ratio.

5. Converting Square Centimeters with 2.54

Areas need the factor squared. One square inch is 6.4516 square centimeters, so divide cm2 by 6.4516.

6. Rounding Too Early

Rounding 76 cm to 29.9 in and then to a fraction gives 29 7/8 in. The unrounded 29.9213 in gives 29 15/16 in at 1/16.

The conversion is exact, because an inch is defined as 2.54 cm. The only rounding is the fraction you choose and the decimals shown.

One centimeter is 0.3937 in. On a tape marked in sixteenths it is closest to 3/8 in, which is 0.475 mm short.

Multiply the centimeters by 4 and divide by 10. The result is 1.6 percent high, so take off about 1/60 of it. For 50 cm: 20 in minus 0.3 in is 19.7 in; the exact value is 19.685 in.

Five centimeters is 1.9685 in. That is 1 15/16 in to the nearest sixteenth, or almost exactly 2 in on a rough ruler.

One inch is exactly 2.54 cm by definition. The value has been fixed since July 1, 1959.

A height of 180 cm is 70.87 in, which is 5 ft 10 7/8 in. Most height charts round it to 5 ft 11 in.

A 32 in waist is 81.28 cm. Measurements from about 80 to 82 cm usually match a size-32 label, but charts vary by brand.

No. Thirty centimeters is 11.811 in, and 12 in is 30.48 cm. The difference is 4.8 mm, about 3/16 in.

Divide the diagonal in cm by 2.54. A 165 cm screen is 64.96 in and is sold as a 65 in model.

They round the factor. Using 0.39 makes answers about 0.94 percent low, which is 0.6 in short on a 170 cm height.

One hundred centimeters, or one meter, is 39.3701 in. That is 3 ft 3 3/8 in to the nearest sixteenth.

• Exact conversion factor: inch to centimeter, 2.54 E+00 (NIST SP 811, Appendix B.8).
• The standard inch of exactly 25.4 millimeters from July 1, 1959 (Federal Register Notice 59-5442, hosted by NIST).
• The 24 SI prefixes, including centi (one hundredth) (NIST Office of Weights and Measures, Metric SI Prefixes).
• UK definitions of the yard (0.9144 m) and the inch (1/36 yard) (Weights and Measures Act 1985, Schedule 1, legislation.gov.uk).