Inches to CM Converter
Translate a US customary length — a photo print, a TV diagonal, lumber or a waist measurement — into centimetres for a metric tape or a European size chart.
Updated
How to use
- Type the length in inches. Use a decimal for fractions (8.5, not 8 1/2).
- Read the centimetre result. Twelve inches always land on 30.48 cm.
- For a thickness or fastener written as 1/4 in or 3/8 in, convert that fraction first (0.25, 0.375) or use the millimetre page.
- Switch to centimetres → inches when the original number was metric.
How it works
This direction is the one people use when a US listing, a school worksheet or a hardware bin is marked in inches and the next tool in their hand is a metric tape. The conversion is a multiply: centimetres = inches × 2.54. That constant is the definition of the inch, so a foot (12 in) is exactly 30.48 cm and a yard (36 in) is exactly 91.44 cm.
Photo prints are a typical case. A 4×6 inch print is 10.16 × 15.24 cm. An 8×10 is 20.32 × 25.4 cm. Frame shops in metric countries still sell those inch names; this page turns the name into a number you can mark on a centimetre ruler.
Screen diagonals work the same way. A 15.6 inch laptop panel is 39.624 cm on the diagonal — not the width of the bezel. Phone listings that say 6.1 inches are also diagonals. Converting the inch figure does not tell you the aspect ratio or the usable width.
Lumber and pipe are messier. A US “2×4” is a nominal name; the dressed board is closer to 1.5 × 3.5 inches (3.81 × 8.89 cm). This converter will happily turn 2 and 4 into 5.08 and 10.16 cm, which is the nominal size, not the board you pick up. Read the actual dressed dimensions if you are cutting to fit.
Fractions of an inch belong here once they are decimals. 5/8 in is 0.625 × 2.54 = 1.5875 cm. If you need millimetres for a workshop drawing, multiply the centimetre result by 10 or use the inches-to-millimetres page so the extra zero is not a mental step.
Formula
centimeters = inches × 2.54
Worked examples
One foot on a US tape
12 in → 30.48 cm
A 4×6 photo short side
4 in → 10.16 cm
Laptop diagonal
15.6 in → 39.624 cm
Inch marks you meet on US products
| in | cm |
|---|---|
| 1 | 2.54 |
| 6 | 15.24 |
| 8 | 20.32 |
| 12 | 30.48 |
| 24 | 60.96 |
| 36 | 91.44 |
Useful notes
- A US customary foot is 12 inches, so 1 ft = 30.48 cm exactly.
- Enter fractions as decimals: 1/8 = 0.125, 1/4 = 0.25, 3/8 = 0.375, 1/2 = 0.5.
- Nominal lumber sizes are names. Convert the dressed measurement if you need a fit.
FAQ
- How many centimeters are in one inch?
Exactly 2.54 centimetres. The inch is defined that way internationally, so the figure is not rounded.
- How many centimeters are in a foot?
A foot is 12 inches, so 12 × 2.54 = 30.48 centimetres exactly.
- How do I convert 5 feet 7 inches to centimetres?
Turn the height into inches first: 5 × 12 + 7 = 67 in. Then 67 × 2.54 = 170.18 cm.
- Why is a 2×4 not 5.08 × 10.16 cm at the store?
Those numbers are the nominal name. The dressed board is smaller. Convert the measured thickness and width, not the name.
- Is this the same as converting cm to inches?
It uses the same 2.54 definition in the opposite direction: multiply inches instead of dividing centimetres.
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