Authoritative definitions of the International System of Units and SI prefixes.
Dedicated unit pair
Millimetres to Centimetres
Convert mm to cm instantly, then review the formula, assumptions, and rounding guidance.
Length & distanceInstant result
Decimals
Formula result = input × 0.001 ÷ 0.01. 1 mm = 0.1 cm
Common examples
One value, several units
Metres0.001 m
Kilometres0 km
Centimetres0.1 cm
Miles0 mi
Yards0.0011 yd
Feet0.0033 ft
Inches0.0394 in
Nautical miles0 nmi
Conversion table
| mm | cm |
|---|---|
| 1 mm | 0.1 cm |
| 2 mm | 0.2 cm |
| 5 mm | 0.5 cm |
| 10 mm | 1 cm |
| 25 mm | 2.5 cm |
| 50 mm | 5 cm |
| 100 mm | 10 cm |
Conversion chart
1 mm0.1 cm
5 mm0.5 cm
10 mm1 cm
25 mm2.5 cm
50 mm5 cm
Worked example
1 metre equals 3.28084 feet.
Unit definition
Millimetres (mm) One millimetres equals 0.001 metre.
Unit history
Millimetres is represented here using its modern SI definition or an internationally accepted relationship to an SI base unit.
Step by step
1. Parse the value, including fractions.
2. Convert mm to metre.
3. Convert the base value to cm and apply your display precision.
Understand the result before using it
Millimetres to Centimetres converts a value measured in Millimetres (mm) into the equivalent value in Centimetres (cm). The numerical value changes because the size and definition of the selected unit changes; the underlying quantity does not.
Calculated result
The conversion follows the displayed unit relationship. Display rounding can hide additional digits, and measured inputs cannot become more accurate merely by changing units.
Formula, assumptions, and example
Formula
result = input × 0.001 ÷ 0.01
Assumptions
- Millimetres and Centimetres represent the same length & distance quantity.
- The input is expressed in mm; the output is expressed in cm.
- The unit definitions and conventional relationship shown on this page apply.
Worked example
1 mm = 0.1 cm. For another value, apply the same relationship and round only to the precision your source measurement supports.
When to use it
Good uses
- Read a mm measurement in a document that expects cm.
- Compare a millimetres value with a value reported in centimetres.
- Check the mm-to-cm arithmetic before copying the result into another calculation.
Limitations
Common mistakes to avoid
- Do not confuse mm with another unit that has a similar name or symbol.
- Round the output to a precision justified by the original measurement.
- Verify safety-critical, regulated, laboratory, and contractual conversions against the controlling standard.
Sources and further reading
These references explain the underlying standards or provide authoritative context. Your own contract, institution, clinician, product documentation, local code, or governing standard may be the controlling source.
Guidance on unit names, symbols, conversions, and numerical presentation.
Questions about this calculation
How do I convert Millimetres to Centimetres?
result = input × 0.001 ÷ 0.01 Using the displayed relationship, 1 mm equals 0.1 cm.
How many Centimetres are in one Millimetres?
One Millimetres is 0.1 Centimetres. The displayed digits may be rounded.
Can I reverse the mm to cm conversion?
Yes. Swap the source and target units in the converter. The reverse relationship converts cm back to mm.
Is the Millimetres to Centimetres result exact?
The conversion follows the displayed unit relationship. Display rounding can hide additional digits, and measured inputs cannot become more accurate merely by changing units.