25 mm to cm
- Millimeters (mm)
- 25 mm
- Centimeters
- 2.5 cm
Checked against: Exact-fraction computation from the legal unit definitions
Millimeters to centimeters converter
Convert millimeters to centimeters (mm to cm) with the exact factor, a conversion chart and worked steps.
By AdminDrafted with AI writing toolsUpdated Checked examples: 3
Centimeters
cm
Centimeters: 2.5 cm
- Conversion
- 25 mm = 2.5 cm
- 1 cm in millimeters
- 10mm
25 mm is about 2.5 cm. In the other direction, 1 cm ≈ 10 mm.
Millimeters to centimeters
Mm to cm chart
| Millimeters | Centimeters |
|---|---|
| 1 | 0.1 |
| 2 | 0.2 |
| 5 | 0.5 |
| 10 | 1 |
| 15 | 1.5 |
| 20 | 2 |
| 25 | 2.5 |
| 30 | 3 |
| 50 | 5 |
| 75 | 7.5 |
| 100 | 10 |
| 500 | 50 |
How it's calculated S
Conversion factor
Exact by definition.
Multiply
About the millimeters to centimeters converter
To convert millimeters to centimeters, multiply by 0.1; to convert back, multiply by 10. For example, 25 mm is about 2.5 cm. Displayed factors and results may be rounded.
Millimeter readings are useful for small clearances, fasteners and drawing dimensions. Retain the tolerance with the original measurement: converting the number cannot make a manufactured part more accurate. Check whether a nominal part size describes its actual measured diameter.
millimetre: 1 mm = 1/1,000 m. The metre is the SI base unit of length.
Both units are defined exactly. Calculations use 50 significant digits and round only for display.
How to convert millimeters to centimeters
Divide millimeters by 10 to get centimeters, which moves the decimal point one place to the left. 10 mm = 1 cm, 11 mm = 1.1 cm and 1 mm = 0.1 cm. Use it to restate a ruler, caliper or drawing measurement in centimeters.
Splitting millimeters into centimeters
A centimeter is ten millimeters (NIST), so on a metric ruler every tenth small mark is a centimeter. 42 mm is 4 cm and 2 mm, written 4.2 cm: the first decimal place counts whole millimeters.
Part of a millimeter goes in the second decimal place. 40.5 mm is 4.05 cm, not 4.5 cm, and 0.5 mm is 0.05 cm.
Fractions divide the same way, though some repeat: a third of a millimeter is 0.0333333333333 cm.
Millimeters to centimeters chart
| Millimeters (mm) | Centimeters (cm) |
|---|---|
| 0.1 | 0.01 |
| 0.5 | 0.05 |
| 1 | 0.1 |
| 2 | 0.2 |
| 5 | 0.5 |
| 10 | 1 |
| 11 | 1.1 |
| 15 | 1.5 |
| 25 | 2.5 |
| 42 | 4.2 |
| 50 | 5 |
| 100 | 10 |
| 300 | 30 |
Where millimeter readings come from
Rainfall, screw lengths and metric engineering drawings are given in millimeters, while everyday descriptions tend to use centimeters. 25 mm of rain is 2.5 cm, and a ruler marked to 300 mm is a 30 cm ruler.
Paper sizes are defined in millimeters too: an A4 sheet is 210 × 297 mm, or 21 × 29.7 cm.
Common mistakes
- Moving the point two places. 11 mm is 1.1 cm, not 0.11 cm. Dividing by 100 is the rule for centimeters to meters; millimeters to meters divides by 1,000.
- Losing a zero. 10.5 mm is 1.05 cm; 1.5 cm would be 15 mm.
- Converting the number but not the tolerance. ±0.5 mm becomes ±0.05 cm. The unit changes; the measurement is no more precise.
- Dividing an area or volume by 10. 100 mm² make 1 cm², so a 42 × 20 mm label (840 mm²) is 8.4 cm². 1,000 mm³ make 1 cm³, so 2,500 mm³ is 2.5 cm³, or 2.5 mL.
Related conversions
For the reverse direction, use cm to mm, and for inch rulers, mm to inches. The length converter covers meters and other lengths; squared and cubed units go in the area converter and volume converter.
Worked examples
15 mm to cm
- Millimeters (mm)
- 15 mm
- Centimeters
- 1.5 cm
Checked against: Exact-fraction computation from the legal unit definitions
100 mm to cm
- Millimeters (mm)
- 100 mm
- Centimeters
- 10 cm
Checked against: Exact-fraction computation from the legal unit definitions
Questions
How many centimeters are in one millimeter?
1 mm is about 0.1 cm. millimetre: 1 mm = 1/1,000 m. The metre is the SI base unit of length.
How do I convert millimeters to centimeters?
Multiply by 0.1: 25 mm × 0.1 ≈ 2.5 cm. To convert back, divide by the same factor. The factor shown may be rounded.
About this calculator
Sources
Checked against references
This calculator includes 3 worked examples with independently sourced answers. They run in the test suite, and you can run them here too.