Inches to CM Converter
Convert inches to centimetres — one inch is exactly 2.54 cm, a definition rather than a measurement. Results update as you type; exact factors shown.
One inch is 2.54 centimetres — see the exact factor, not a rounded rule of thumb.
How the inches to cm converter works
Every length is converted through the metre, the SI base unit of length. The inch has been defined as exactly 25.4 mm since the 1959 international yard and pound agreement, so a foot is exactly 0.3048 m, a yard 0.9144 m and a statute mile 1,609.344 m. The nautical mile is 1,852 m by international definition.
Australia is fully metric under the National Measurement Act 1960; imperial units appear only in trade with the US and in older documents.
Common length conversions
| From | To | Units |
|---|---|---|
| 1 in | 2.54 cm | inch to centimetres |
| 2 in | 5.08 cm | inchs to centimetres |
| 3 in | 7.62 cm | inchs to centimetres |
| 6 in | 15.24 cm | inchs to centimetres |
| 8 in | 20.32 cm | inchs to centimetres |
| 10 in | 25.4 cm | inchs to centimetres |
| 12 in | 30.48 cm | inchs to centimetres |
| 18 in | 45.72 cm | inchs to centimetres |
| 24 in | 60.96 cm | inchs to centimetres |
| 36 in | 91.44 cm | inchs to centimetres |
| 48 in | 121.92 cm | inchs to centimetres |
| 72 in | 182.88 cm | inchs to centimetres |
Units in this converter and their exact factors
| Unit | Symbol | One unit in metres |
|---|---|---|
| millimetre | mm | 0.001 metre |
| centimetre | cm | 0.01 metre |
| metre | m | 1 metre |
| kilometre | km | 1,000 metre |
| inch | in | 0.0254 metre |
| foot | ft | 0.3048 metre |
| yard | yd | 0.9144 metre |
| mile | mi | 1,609.344 metre |
| nautical mile | nmi | 1,852 metre |
FAQFrequently asked questions about length conversion
How many cm is 1 inch?
Exactly 2.54 cm. It is a definition agreed internationally in 1959, not a rounded figure.
How do I convert inches to cm quickly?
Multiply by 2.5 and add a bit: 10 inches is about 25 cm, and exactly 25.4.
What is 12 inches in cm?
30.48 cm — a foot.
What size is a 32-inch waist in cm?
81.28 cm, usually sold as 81 or 82 cm.
Do screen sizes work the same way?
Yes, but a screen is measured diagonally — a 27-inch monitor is 68.58 cm corner to corner, not across.
Where these figures come from
- BIPM — The International System of Units (SI Brochure, 9th edition) — definitions of the base and derived units.
- NIST Special Publication 811 — Guide for the Use of the International System of Units — the exact conversion factors used here.
- National Measurement Institute (NMI) — Australia's national measurement authority.
Last checked: September 2026. Conversion factors are fixed by definition and do not change with tax years or regulations.