CM to MM Converter
Convert centimetres to millimetres quickly. Free online cm to mm calculator with common conversions and formula.
Formula
mm = cm × 10
Common Conversions
How to Convert Centimetres to Millimetres
1 cm = 10 mm. Multiply centimetres by 10 (or move the decimal point one place right) to get millimetres. So 25 cm = 250 mm. The simplest possible conversion - just multiply by 10.
Useful when scaling up from everyday metric measurements (cm, used for clothing, body dimensions) to engineering-precision metric (mm, used for fastener sizes, machined parts). A 30 cm ruler is 300 mm; a 12.5 cm cake tin is 125 mm.
Common Centimetres to Millimetres Conversions
| Centimetres | Millimetres |
|---|---|
| 0.5 cm | 5 mm |
| 1 cm | 10 mm |
| 2.5 cm | 25 mm |
| 5 cm | 50 mm |
| 10 cm | 100 mm |
| 25 cm | 250 mm |
| 50 cm | 500 mm |
| 100 cm (1 m) | 1000 mm |
Frequently Asked Questions
Are mm marks on a ruler the same as cm marks?
No - mm marks are 10 times denser. A ruler marked in cm has 10 mm marks between each cm. The big numbered marks are usually cm; the smaller subdivisions are mm.
What's a common precision measurement in mm?
Fastener thickness (M6 = 6 mm), wire gauge, paper thickness (80 gsm paper is about 0.1 mm), and pen tip width (medium pen ≈ 0.7 mm). mm is the unit of choice for sub-cm dimensions in technical work.
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