Centimetres to inches
Convert centimetres to inches and back using the exact international factor, with a reference chart and the formula shown.
1 cm = 0.3937007874 in
inches = centimetres × 0.393700787402
centimetres to inches
| cm | in |
|---|---|
| 1 | 0.393701 |
| 2 | 0.787402 |
| 3 | 1.181102 |
| 4 | 1.574803 |
| 5 | 1.968504 |
| 10 | 3.937008 |
| 15 | 5.905512 |
| 20 | 7.874016 |
| 25 | 9.84252 |
| 50 | 19.685039 |
| 75 | 29.527559 |
| 100 | 39.370079 |
| 500 | 196.850394 |
| 1,000 | 393.700787 |
One centimetre is exactly 0.393700787402 inches.
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The formula
inches = centimetres ÷ 2.54
centimetres = inches × 2.54The factor 2.54 is exact by definition, established by the 1959 International Yard and Pound Agreement between the United States, United Kingdom, Canada, Australia, New Zealand and South Africa. Before that agreement, the US inch and the imperial inch differed very slightly - enough to matter in precision engineering.
Quick reference
| cm | inches | cm | inches |
|---|---|---|---|
| 1 | 0.3937 | 30 | 11.811 |
| 2 | 0.7874 | 40 | 15.748 |
| 5 | 1.9685 | 50 | 19.685 |
| 10 | 3.9370 | 60 | 23.622 |
| 15 | 5.9055 | 100 | 39.370 |
| 20 | 7.8740 | 180 | 70.866 |
| 25 | 9.8425 | 200 | 78.740 |
Common heights
| Height | Inches | Feet and inches |
|---|---|---|
| 150 cm | 59.06 | 4’11” |
| 160 cm | 62.99 | 5’3” |
| 165 cm | 64.96 | 5’5” |
| 170 cm | 66.93 | 5’7” |
| 175 cm | 68.90 | 5’9” |
| 180 cm | 70.87 | 5’11” |
| 185 cm | 72.83 | 6’1” |
| 190 cm | 74.80 | 6’3” |
To convert a height yourself: divide centimetres by 2.54 for total inches, then divide by 12. The whole number is feet and the remainder is inches.
Where each unit is used
The centimetre is standard almost everywhere for body measurements, clothing, paper sizes, and everyday distances too small for a metre. The inch persists in the United States, and survives worldwide in specific technical niches regardless of the local system:
- Screen sizes. Televisions, monitors and phones are measured diagonally in inches globally.
- Plumbing. Pipe diameters remain in inches in most of the world.
- Tyres and wheels. Rim diameters are in inches even on cars sold in fully metric markets.
- Print. DPI - dots per inch - is universal in publishing.
- Photography. Sensor sizes use an inch-based convention.
Mental arithmetic
Centimetres to inches: divide by 2.5, then subtract about 1.5%. Close enough for shopping and DIY.
Inches to centimetres: multiply by 2.5, then add about 1.5%. So 10 inches → 25 + 0.4 = 25.4 cm, which is exact.
A useful anchor: 30 cm is almost exactly one foot (11.81 inches). A 30 cm ruler and a 12-inch ruler are close enough to be interchangeable for most non-precision work.
Common questions
What is the exact conversion factor?
One inch is exactly 2.54 centimetres. This is not an approximation - it has been the defined value since the International Yard and Pound Agreement of 1959, which fixed the inch in metric terms. So 1 cm = 1 ÷ 2.54 = 0.3937007874… inches, a repeating decimal.
How do I convert in my head?
Divide by 2.5 and subtract about 1.5%. For 30 cm, 30 ÷ 2.5 = 12, minus 1.5% gives 11.82 - the true answer is 11.81. Or remember that 2.5 cm is almost exactly an inch, so centimetres divided by 2.5 is close enough for most practical purposes.
What height is 170 cm in feet and inches?
170 cm is 66.93 inches, which is 5 feet 6.93 inches - commonly written as 5'7". To convert any height, divide the inches by 12 for the feet, and the remainder is the inches.
Why does the US still use inches?
The US formally adopted metric as its preferred system in 1975 but never made it mandatory, so customary units persisted in everyday use. Notably the inch itself is defined *in terms of* the metre, so American measurements are metric underneath - the definition simply carries a conversion factor.
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