Centimeters to Millimeters Converter

Centimeters to Millimeters

Convert centimeters (cm) to millimeters (mm). Both measure distance and dimension, and the conversion comes up in construction, navigation, sports work.

The Formula

`` millimeters = centimeters × 10 centimeters = millimeters × 0.1 `

One centimeter is 10 millimeters, and one millimeter is 0.1 centimeters.

Conversion Table

Centimeters	Millimeters
1 cm	10 mm
2 cm	20 mm
5 cm	50 mm
10 cm	100 mm
25 cm	250 mm
50 cm	500 mm
100 cm	1,000 mm
500 cm	5,000 mm
1,000 cm	10,000 mm

The Other Direction

Millimeters	Centimeters
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
500 mm	50 cm
1,000 mm	100 cm

What Each Unit Is

Centimeters (cm) — one hundredth of a metre. A metric subdivision, and the everyday unit for body and object measurements in metric countries.

Millimeters (mm) — one thousandth of a metre. The metric unit engineering drawings default to, because it removes decimal points from most dimensions.

A Sense of Scale

• A fingernail is about 1 cm wide
• A credit card is 8.6 cm long
• A4 paper is 21 cm wide
• A credit card is 0.76 mm thick
• A paperclip wire is about 1 mm
• Rainfall is measured in mm

Precision

The factor 10 is rounded. For engineering work carry more digits than the table above, and round only at the end — rounding at each step compounds.

In Code

`javascript const centimeterToMillimeter = (value) => value * 10; ``

Where This Conversion Comes Up

• Construction
• Navigation
• Sports
• Sewing
• Mapping

How Many Decimals Do You Need?

Rounding the factor costs accuracy, and how much depends on the factor. Converting 137 cm with the factor truncated at each decimal place:

Decimals kept	Factor	137 cm becomes	Error
0	10	1,370	—
1	10	1,370	—
2	10	1,370	—
3	10	1,370	—
4	10	1,370	—

A rule that holds for any conversion: round once, at the end. Rounding the factor and then multiplying compounds the error through every subsequent calculation, while carrying full precision and rounding the final answer does not.

The right number of significant figures is set by your input, not by the converter. If you measured centimeters to three significant figures, the answer in millimeters is only good to three — writing more digits claims precision the measurement never had.