Convert inches to cm exactly, including fractions and feet and inches, or switch to cm to inches.
| Inches | Centimetres |
|---|
1 inch is exactly 2.54 cm under the 1959 international yard and pound agreement, so every result here is exact before rounding.
This inches to cm converter turns any length in inches into centimetres for readers in the UK, US, Europe and anywhere else that mixes imperial and metric sizes. It accepts decimals, tape measure fractions such as 5 3/8 and feet plus inches, and it uses the exact factor fixed by the international yard and pound agreement of 1959, so a result never drifts from the official value. You also get millimetres, metres and the nearest sixteenth of an inch.
Quick answer: To convert inches to cm, multiply the number of inches by 2.54. One inch is exactly 2.54 centimetres, so 12 inches is 30.48 cm and 10 inches is 25.4 cm. For feet and inches, multiply the feet by 12, add the inches, then multiply the total by 2.54.
In This Guide
What Is an Inches to CM Conversion?
An inches to cm conversion changes a length measured in the imperial inch into the metric centimetre by multiplying it by 2.54. The inch belongs to the imperial and US customary systems, while the centimetre is one hundredth of a metre in the metric system used by most of the world.
The formula is centimetres = inches × 2.54, and the reverse is centimetres ÷ 2.54. Because 2.54 is exact rather than rounded, the only error in any answer comes from how many decimal places you choose to show. Multiply the centimetres by 10 for millimetres, or divide by 100 for metres.
How to Use the Inches to CM Converter
Step 1: Choose the Direction
Leave the toggle on Inches to cm for the usual conversion, or switch to cm to inches when you start from a metric figure. Switching keeps your current length, so you can flip back and forth without retyping.
Step 2: Enter the Length
Type inches as a decimal (7.5), a fraction (3/4) or a mixed number (5 3/8), exactly as it appears on a tape measure. Choose Feet + inches for heights and room sizes, such as 5 ft 7 in.
Step 3: Pick the Decimal Places
Two decimal places suit most everyday jobs, from clothing to picture frames. Choose 3 or 4 when you are working to engineering drawings, where a tenth of a millimetre matters.
Step 4: Read the Results
The main figure shows centimetres, with the sum written out underneath so you can check it. When your starting figure is metric, the cm to inches converter has its own table and examples for that direction. This panel also shows millimetres, metres, feet and inches, the nearest 1/16 inch and a small table of the whole inches around your value.
How Many Centimetres Are in an Inch?
There are exactly 2.54 centimetres in one inch, which is the same as 25.4 millimetres. This has been the legal definition since 1959, when the UK, the US and other Commonwealth countries agreed a common inch, so the figure is identical whether you are converting inches to centimeters in New York or in Newcastle.
Inches to CM Conversion Table
| Inches | Centimetres | Common use |
|---|---|---|
| 1/4 in | 0.635 cm | Seam allowance |
| 1/2 in | 1.27 cm | Bolt or pipe size |
| 1 in | 2.54 cm | Base unit |
| 6 in | 15.24 cm | Half a ruler |
| 12 in (1 ft) | 30.48 cm | School ruler |
| 15.6 in | 39.62 cm | Laptop screen diagonal |
| 24 in | 60.96 cm | Desktop monitor diagonal |
| 36 in (1 yd) | 91.44 cm | Door width, fabric yard |
| 55 in | 139.7 cm | Television diagonal |
| 65 in | 165.1 cm | Large television diagonal |
Screen sizes are measured across the diagonal, not the width, so a 55 inch television is 139.7 cm corner to corner but narrower than that from side to side.
How Do I Convert Feet and Inches to CM?
To convert feet and inches to cm, multiply the feet by 12, add the remaining inches and multiply the total by 2.54. A height of 5 ft 7 in is 5 × 12 + 7 = 67 inches, and 67 × 2.54 = 170.18 cm, which most forms round to 170 cm.
Worked example: Priya is fitting a blind into a window recess her tape measure reads as 2 ft 9 3/8 in wide. That is 24 + 9.375 = 33.375 inches, and 33.375 × 2.54 = 84.77 cm. The blind supplier sells in centimetres, so she orders an 84 cm blind to leave a small gap at each side.
Heights work the same way. If you are entering a height on a health form, the BMI calculator accepts feet and inches directly and converts them to centimetres, so there is no need to do the sum by hand first.
How Do I Convert Fractions of an Inch to CM?
To convert a fraction of an inch to cm, divide the top number by the bottom number to get a decimal, then multiply by 2.54. For example, 3/8 in is 0.375 in, which is 0.9525 cm or about 9.5 mm. This tool reads fractions directly, so you can type 3/8 or 5 3/8 without working out the decimal first.
Tape measures in the US and many UK trade tapes mark sixteenths of an inch, so each small mark is 1.5875 mm. For other units such as yards, metres and miles in one place, the length converter handles every common distance, and the history of the inch explains why the old barleycorn definition was replaced. Figures checked October 2026.
Key Inches to CM Terms Explained
These units and standards sit behind every inches to cm conversion on this page, from the exact 2.54 factor to tape measure fractions.
- Inch
- An imperial and US customary unit of length equal to exactly 2.54 centimetres. Twelve inches make one foot and thirty six inches make one yard, which is why the tool can also show results as feet and inches.
- Centimetre
- A metric unit of length equal to one hundredth of a metre, or 10 millimetres. It is the everyday unit for heights, clothing and furniture across most of Europe and the rest of the metric world.
- International yard and pound
- The 1959 agreement between the UK, the US and other Commonwealth countries that defined the yard as exactly 0.9144 metres. Dividing that by 36 gives the exact 2.54 centimetre inch used by this converter.
- Sixteenth of an inch
- The smallest mark on most imperial tape measures, equal to 1.5875 millimetres. The converter rounds to the nearest sixteenth so you can find a metric length on an imperial tape.
- Screen diagonal
- The way televisions, monitors and laptops are sized, measured corner to corner across the visible screen in inches. A 15.6 inch laptop screen is 39.62 centimetres on the diagonal, not across its width.
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How we checked this tool: the Tools Veria Editorial Team built this tool by hand, checked it against the official rules or published standards where they apply, and tested it against worked examples. Results are estimates for planning, not personal financial or tax advice. Read our editorial policy and disclaimer, or report an error.
Frequently Asked Questions
How many cm is 1 inch exactly?
One inch is exactly 2.54 centimetres, or 25.4 millimetres. This value was fixed by international agreement in 1959 and is not rounded, so any conversion using 2.54 is precise to as many decimal places as you need.
How do I convert inches to cm quickly in my head?
Multiply the inches by 2.5 for a fast estimate, then add a little. For example, 20 inches × 2.5 = 50, and the exact answer is 50.8 cm. The shortcut is always about 1.6% too low.
How many cm is 5 ft 7 in?
5 ft 7 in is 170.18 cm. Multiply 5 feet by 12 to get 60 inches, add 7 to make 67 inches, then multiply 67 by 2.54 to get 170.18 centimetres.
How many cm is a 55 inch TV?
A 55 inch TV measures 139.7 cm across the diagonal of the screen. The width is smaller: for a standard 16:9 screen it is roughly 121.8 cm wide and 68.5 cm high, before adding the frame and stand.
Is an inch bigger than a centimetre?
Yes, an inch is 2.54 times longer than a centimetre. That means there are just over two and a half centimetres in every inch, and about 0.3937 of an inch in every centimetre.
What is 3/4 of an inch in cm?
Three quarters of an inch is 1.905 cm, or about 19 mm. Divide 3 by 4 to get 0.75 inches, then multiply by 2.54 to convert the decimal inches into centimetres.