Centimeters to Millimeters Converter

1 centimeter (cm) equals 10 millimeters (mm).

Quick answer

To convert centimeters to millimeters, multiply by 10: 2.5 cm = 25 mm.

  • 1 centimeter = 10 millimeters
  • 1 millimeter = 0.1 centimeters
  • Formula: mm = cm × 10
  • Quick estimate: move the decimal point one place right: 3.2 cm = 32 mm.

1 centimeter = 10 millimeters

How to convert centimeters to millimeters

mm = cm × 10

To convert centimeters to millimeters, multiply the number of centimeters by 10.

Example: 42 cm to mm

  1. Start with the value in centimeters: 42 cm.
  2. Multiply by 10: 42 × 10 = 420.
  3. Result: 42 centimeters = 420 millimeters.

Going the other way, 1 millimeter = 0.1 centimeters, so to convert millimeters back to centimeters you divide by the same number. See millimeters to centimeters.

Where the conversion factor comes from

The meter is the SI base unit of length, defined since 1983 as the distance light travels in a vacuum in 1/299,792,458 of a second. Metric prefixes are exact powers of ten: 1 m = 100 cm = 1,000 mm, and 1 km = 1,000 m.

Mental math: cm to mm in your head

Move the decimal point one place to the right.

When you need to convert centimeters to millimeters

  • Engineering drawings, which are usually dimensioned in mm.
  • Screen and camera sensor sizes.

Common mistakes

  • Multiplying by 100 instead of 10.

Everyday centimeters in millimeters

ExampleCentimetersMillimeters
Fingernail width1 cm10 mm
Postage stamp2.5 cm25 mm
Business card width8.5 cm85 mm
A4 paper width21 cm210 mm

Centimeters to millimeters conversion table

Centimeters (cm)Millimeters (mm)
0.1 cm 1 mm
0.2 cm 2 mm
0.3 cm 3 mm
0.4 cm 4 mm
0.5 cm 5 mm
0.6 cm 6 mm
0.7 cm 7 mm
0.8 cm 8 mm
0.9 cm 9 mm
1 cm 10 mm
1.5 cm 15 mm
2 cm 20 mm
2.5 cm 25 mm
3 cm 30 mm
3.5 cm 35 mm
4 cm 40 mm
4.5 cm 45 mm
5 cm 50 mm
6 cm 60 mm
7 cm 70 mm
7.5 cm 75 mm
8 cm 80 mm
9 cm 90 mm
10 cm 100 mm
11 cm 110 mm
12 cm 120 mm
13 cm 130 mm
14 cm 140 mm
15 cm 150 mm
16 cm 160 mm
17 cm 170 mm
18 cm 180 mm
19 cm 190 mm
20 cm 200 mm
21 cm 210 mm
22 cm 220 mm
23 cm 230 mm
24 cm 240 mm
25 cm 250 mm
26 cm 260 mm

More cm to mm values

What is a centimeter?

The centimeter (also spelled centimetre) is a metric unit of length equal to one hundredth of a meter.

More about centimeters →

What is a millimeter?

The millimeter (also spelled millimetre) is a metric unit of length equal to one thousandth of a meter, or one tenth of a centimeter.

More about millimeters →

Convert centimeters to other units

Convert other units to millimeters

Frequently asked questions

How many millimeters are in a centimeter?

One centimeter is 10 millimeters.

How many centimeters are in a millimeter?

One millimeter is 0.1 centimeters.

What is the formula to convert centimeters to millimeters?

mm = cm × 10.

How many mm is 5 cm?

50 millimeters.