MM to CM Converter
Convert millimeters to centimeters — ten to the centimeter. Results update as you type; exact factors shown.
One millimeter is 0.1 centimeters — see the exact factor, not a rounded rule of thumb.
How the mm 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 mm | 0.1 cm | millimeter to centimeters |
| 5 mm | 0.5 cm | millimeters to centimeters |
| 10 mm | 1 cm | millimeters to centimeters |
| 12 mm | 1.2 cm | millimeters to centimeters |
| 15 mm | 1.5 cm | millimeters to centimeters |
| 20 mm | 2 cm | millimeters to centimeters |
| 25 mm | 2.5 cm | millimeters to centimeters |
| 50 mm | 5 cm | millimeters to centimeters |
| 100 mm | 10 cm | millimeters to centimeters |
| 150 mm | 15 cm | millimeters to centimeters |
| 250 mm | 25 cm | millimeters to centimeters |
| 1,000 mm | 100 cm | millimeters 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 mm in a cm?
Ten.
What is 250 mm in cm?
25 cm.
How do I convert quickly?
Move the decimal point one place left.
Which is used on drawings?
Millimeters, because most part dimensions come out whole.
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.