Cm to Inches Converter
Convert centimeters to inches, or inches to centimeters, with feet and inches, the nearest 1/16 inch, millimeters and meters.
Results
| Item | Value |
|---|
Quick Answer
Divide centimeters by 2.54 to get inches. 1 cm is 0.3937 in, 10 cm is 3.94 in, 30 cm is 11.81 in and 100 cm is 39.37 in. To turn inches into centimeters, multiply by 2.54: 6 in is 15.24 cm and 12 in (1 foot) is 30.48 cm.
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Table of Contents
- Cm to Inches Converter
- Quick Answer
- Related Calculators
- How This Cm to Inches Converter Works
- How to Use the Cm to Inches Converter
- Cm to Inches Formulas
- Key Terms
- Worked Example
- Real-Life Examples
- Centimeter vs Inch
- Centimeters to Inches Chart
- Reading a Ruler in Inches
- Common Mistakes to Avoid
- Frequently Asked Questions
- References & Sources
How This Cm to Inches Converter Works
Clothing sizes, screen sizes, furniture and height often come in one unit when you need the other. Pick the direction, enter the length and press Calculate. You get the answer to two decimal places, the nearest 1/16 inch to read on a tape measure, feet and inches, millimeters and meters, plus the formula.
Quick explanation: one inch is exactly 2.54 centimeters.
- cm to in: divide by 2.54.
- in to cm: multiply by 2.54.
- Mental math: 10 cm is just under 4 inches.
How to Use the Cm to Inches Converter
- Choose centimeters to inches or inches to centimeters.
- Enter the length.
- Press Calculate.
- Read the converted length, the nearest 1/16 inch, feet and inches, mm and m.
Cm to Inches Formulas
- Definition: 1 inch (in) = 2.54 centimeters exactly
- Inches from centimeters: in = cm ÷ 2.54 = cm × 0.393701
- Centimeters from inches: cm = in × 2.54
- Feet: 1 ft = 12 in = 30.48 cm
- Millimeters: 1 cm = 10 mm, so 1 in = 25.4 mm
Key Terms
- Centimeter (cm): one hundredth of a meter; 10 millimeters.
- Inch (in): exactly 2.54 cm; 12 inches make a foot.
- Foot (ft): 12 inches, or 30.48 cm.
- Millimeter (mm): one thousandth of a meter.
- 1/16 inch: the smallest mark on most US tape measures, about 1.6 mm.
Worked Example
How tall is a person who is 170 cm?
- 170 ÷ 2.54 = 66.9291 in
- 66.9291 ÷ 12 = 5 feet with 6.93 in left over
- So 170 cm is about 5 ft 7 in (5 ft 6.93 in).
Going the other way, a 32 in waist is 32 × 2.54 = 81.28 cm.
Real-Life Examples
- Height: 160 cm is 63.0 in and 180 cm is 70.9 in.
- Screens: a 65 in TV diagonal is 165.1 cm.
- Clothing: an 81 cm waist is 31.9 in.
- Paper: A4 is 21.0 × 29.7 cm, or 8.27 × 11.69 in.
Centimeter vs Inch
- Centimeter (cm): one hundredth of a meter, used for length in most countries.
- Inch (in): the US customary and imperial unit, exactly 2.54 cm.
- Size: an inch is 2.54 times longer, so 1 cm = 0.3937 in.
Centimeters to Inches Chart
Exact factor: 1 in = 2.54 cm.
| Centimeters | Inches | Nearest 1/16 in |
|---|---|---|
| 1 cm | 0.39 in | 3/8 in |
| 2 cm | 0.79 in | 13/16 in |
| 2.5 cm | 0.98 in | 1 in |
| 5 cm | 1.97 in | 1 15/16 in |
| 10 cm | 3.94 in | 3 15/16 in |
| 15 cm | 5.91 in | 5 7/8 in |
| 20 cm | 7.87 in | 7 7/8 in |
| 25 cm | 9.84 in | 9 13/16 in |
| 30 cm | 11.81 in | 11 13/16 in |
| 40 cm | 15.75 in | 15 3/4 in |
| 50 cm | 19.69 in | 19 11/16 in |
| 60 cm | 23.62 in | 23 5/8 in |
| 75 cm | 29.53 in | 29 1/2 in |
| 100 cm | 39.37 in | 39 3/8 in |
| 150 cm | 59.06 in | 59 1/16 in |
Reading a Ruler in Inches
Tape measures in the US mark inches in halves, quarters, eighths and sixteenths, not decimals. That is why the converter also rounds to the nearest 1/16 inch: 10 cm is 3.9370 in, which a ruler shows as 3 15/16 in. Rounding to 1/16 inch keeps the error under 0.8 mm.
The inch has been defined as exactly 2.54 cm since 1959, so every inch-to-centimeter answer is exact. Only centimeters to inches give a long decimal, because 1 ÷ 2.54 = 0.393700787…
For quick estimates without a calculator, remember a few anchor points: 2.5 cm is about 1 inch, 5 cm is about 2 inches, 30 cm is about 1 foot and 1 meter is about 39.4 inches, a little more than a yard. Body measurements such as height are usually given to the nearest centimeter or the nearest half inch, so two decimal places are more than enough for them. For woodworking and sewing, use the 1/16 inch fraction, because that is the mark you will actually cut or sew to.
Common Mistakes to Avoid
- Multiplying instead of dividing. Centimeters become a smaller number in inches.
- Reading decimals as inches and feet. 66.93 in is 5 ft 6.93 in, not 66 ft 9.3 in.
- Rounding 2.54 to 2.5. 100 in would come out 4 cm too short.
- Mixing cm and mm. 25.4 mm is one inch; 25.4 cm is 10 inches.
- Treating 0.5 ft as 5 in. Half a foot is 6 inches.
Frequently Asked Questions
1 cm is 0.3937 inches.
Divide the centimeters by 2.54.
One inch is exactly 2.54 cm.
30 cm is 11.81 in, just under 1 foot.
100 cm is 39.37 in, or 3 ft 3.37 in.
12 in is 30.48 cm.
170 cm is 5 ft 6.93 in, about 5 ft 7 in.
10 cm is 3.94 in, or about 3 15/16 in.
5 in is 12.7 cm.
References & Sources
| Source | Used For | Link |
|---|---|---|
| NIST, Guide to the SI, Appendix B.8 | Inch = 2.54 cm exactly. | https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8 |
| NIST Handbook 44, Appendix C: General Tables of Units of Measurement | Units of length: inch, foot, yard and their metric equivalents. | https://www.nist.gov/pml/owm/nist-handbook-44-current-edition |