The defining value
- Centimeters
- 2.54
Result Inches: 1
- 2.54 cm × 0.393701 = 1 in
Since 1959 the inch has been fixed at exactly 2.54 cm, so 2.54 cm converts to exactly one inch.
cm to Inches Converter
To convert centimetres to inches, divide by 2.54, or multiply by 0.393701. The inch has been defined as exactly 2.54 cm since 1959, so the result is exact up to rounding. For example, 30 cm is 30 ÷ 2.54 = 11.811 inches, and 100 cm is 39.37 inches.
Centimeters to Inches conversion table
| cm | in |
|---|---|
| 1 | 0.393701 |
| 2 | 0.787402 |
| 5 | 1.9685 |
| 10 | 3.93701 |
| 20 | 7.87402 |
| 25 | 9.84252 |
| 50 | 19.685 |
| 100 | 39.3701 |
| 250 | 98.4252 |
| 500 | 196.85 |
| 1,000 | 393.701 |
About this tool
Clothing size charts, screen sizes, furniture listings and sewing patterns switch between metric and imperial without warning, so a quick centimetre-to-inch conversion comes up constantly. Type a length in centimetres and the inch value appears as you type, together with the division used to reach it. The factor is exact by international definition, so the only error is the display rounding. The converter returns decimal inches, not fractions such as 11 13/16, so woodworkers reading a tape measure in sixteenths will still need to round to the nearest mark. The swap button reverses the direction for inches to centimetres.
How to use it
Enter the length in centimetres
Type the measurement into the centimetres field. Decimals work, for example 152.4 for a height.
Read the inches
The inch value updates as you type, with the working shown underneath.
Swap or share
Use Swap to go from inches to centimetres, or Share to send a link that reopens the same value.
Examples
A 30 cm school ruler
- Centimeters
- 30
Result Inches: 11.811
- 30 cm × 0.393701 = 11.811 in
The common 30 cm ruler is just under 12 inches long, about 11.81 in, so it is slightly shorter than a foot ruler.
One metre
- Centimeters
- 100
Result Inches: 39.3701
- 100 cm × 0.393701 = 39.3701 in
A metre is 100 cm, which works out to about 39.37 inches, a little over a yard.
How it is calculated
in = cm ÷ 2.54
cm- length in centimetres
in- length in international inches
The 1959 international yard and pound agreement fixed the yard at exactly 0.9144 metres, which makes the inch exactly 25.4 millimetres, or 2.54 centimetres. Dividing a centimetre value by 2.54 therefore gives inches with no approximation. Multiplying by 0.393701 gives the same answer to six significant figures.
When not to use it
- Survey drawings in the old US survey inch differ by about 2 parts per million, which matters only over long distances.
- Tape measures marked in fractions need the decimal result rounded to the nearest sixteenth by hand.
Common mistakes
- Multiplying by 2.54 instead of dividing gives a result about 6.5 times too large.
- Entering millimetres in the centimetre field makes the answer ten times too big.
Frequently asked questions
How many inches is 1 cm?
One centimetre is 0.393701 inches, a little under four tenths of an inch. That is the reciprocal of the exact 2.54 cm per inch.
Is 2.54 an exact number or a rounded one?
It is exact. Since 1959 the international inch has been defined as precisely 25.4 millimetres, so 2.54 cm per inch carries no rounding at all.
How do I turn decimal inches into feet and inches?
Divide the inch value by 12. The whole number is feet and the remainder is inches. For example, 170 cm is 66.93 inches, which is 5 feet 6.93 inches.
How many centimetres make a foot?
A foot is 12 inches, so it is 12 × 2.54 = 30.48 cm. A 30 cm ruler is therefore 0.48 cm short of a foot.
Why do screen sizes use inches even in metric countries?
Display makers have quoted diagonals in inches for decades, and the habit stuck worldwide. A 55 inch television has a diagonal of about 139.7 cm.
Cite this tool
Using this tool in an assignment, article or report? Copy a citation, or a link for your website.
APA
Tools Directory Editorial Team. (2026, October 18). cm to Inches Converter. Tools Directory. Retrieved October 26, 2026, from https://tools.milunir.com/converters/length/cm-to-inches-converter/
MLA
Tools Directory Editorial Team. “cm to Inches Converter.” Tools Directory, 18 Oct. 2026, https://tools.milunir.com/converters/length/cm-to-inches-converter/. Accessed 26 Oct. 2026.
Chicago
Tools Directory Editorial Team. “cm to Inches Converter.” Tools Directory. Last modified October 18, 2026. Accessed October 26, 2026. https://tools.milunir.com/converters/length/cm-to-inches-converter/.
Link
<a href="https://tools.milunir.com/converters/length/cm-to-inches-converter/">cm to Inches Converter – Tools Directory</a>