Inches to CM Converter
Convert inches to centimeters — 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 centimeters — see the exact factor, not a rounded rule of thumb.
How the inches to cm converter works
Every length is converted through the meter, 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.
The US uses customary units (US gallon, short ton, °F) in daily life; NIST SP 811 gives the exact SI factors.
Common length conversions
| From | To | Units |
|---|---|---|
| 1 in | 2.54 cm | inch to centimeters |
| 2 in | 5.08 cm | inchs to centimeters |
| 3 in | 7.62 cm | inchs to centimeters |
| 6 in | 15.24 cm | inchs to centimeters |
| 8 in | 20.32 cm | inchs to centimeters |
| 10 in | 25.4 cm | inchs to centimeters |
| 12 in | 30.48 cm | inchs to centimeters |
| 18 in | 45.72 cm | inchs to centimeters |
| 24 in | 60.96 cm | inchs to centimeters |
| 36 in | 91.44 cm | inchs to centimeters |
| 48 in | 121.92 cm | inchs to centimeters |
| 72 in | 182.88 cm | inchs to centimeters |
Units in this converter and their exact factors
| Unit | Symbol | One unit in meters |
|---|---|---|
| millimeter | mm | 0.001 meter |
| centimeter | cm | 0.01 meter |
| meter | m | 1 meter |
| kilometer | km | 1,000 meter |
| inch | in | 0.0254 meter |
| foot | ft | 0.3048 meter |
| yard | yd | 0.9144 meter |
| mile | mi | 1,609.344 meter |
| nautical mile | nmi | 1,852 meter |
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 Institute of Standards and Technology (NIST) — United States's national measurement authority.
Last checked: September 2026. Conversion factors are fixed by definition and do not change with tax years or regulations.