Millimeters to Decimeters (mm to dm) Converter

How to convert millimeters to decimeters

Formuladm = mm × 0.01

Multiply the value in millimeters by 0.01. To go the other way, multiply by 100 (or divide by 0.01).

A millimeter is smaller than a decimeter: it takes 100 millimeters to make one decimeter.

Worked examples

1 millimeter1 mm × 0.01 = 0.01 dm
5 millimeters5 mm × 0.01 = 0.05 dm
10 millimeters10 mm × 0.01 = 0.1 dm
20 millimeters20 mm × 0.01 = 0.2 dm
100 millimeters100 mm × 0.01 = 1 dm

Millimeters to decimeters conversion table

Values are calculated by the conversion engine and rounded to 8 significant figures.

Millimeters to decimeters: 0.1–10 mm
Millimeters (mm)	Decimeters (dm)
0.1 mm	0.001 dm
0.25 mm	0.0025 dm
0.5 mm	0.005 dm
1 mm	0.01 dm
2 mm	0.02 dm
3 mm	0.03 dm
4 mm	0.04 dm
5 mm	0.05 dm
6 mm	0.06 dm
7 mm	0.07 dm
8 mm	0.08 dm
9 mm	0.09 dm
10 mm	0.1 dm

Millimeters to decimeters: 12–1,000 mm
Millimeters (mm)	Decimeters (dm)
12 mm	0.12 dm
15 mm	0.15 dm
20 mm	0.2 dm
25 mm	0.25 dm
30 mm	0.3 dm
40 mm	0.4 dm
50 mm	0.5 dm
75 mm	0.75 dm
100 mm	1 dm
250 mm	2.5 dm
500 mm	5 dm
1,000 mm	10 dm

About the units

Millimeter (mm)

One thousandth of a metre. Millimetres are the standard unit on engineering drawings, rulers and rainfall gauges; a credit card is about 0.76 mm thick. One millimeter equals 0.001 meters (m).

Decimeter (dm)

The decimeter (dm) is a unit of length in the International System of Units (SI). One decimeter equals 0.1 meters (m).

Frequently asked questions

How many decimeters are in one millimeter?

There are 0.01 decimeters in one millimeter, and this value is exact by definition.

How do I convert millimeters to decimeters?

Multiply the number of millimeters by 0.01. For example, 10 mm × 0.01 = 0.1 dm.

How many millimeters are in one decimeter?

One decimeter equals 100 millimeters. That is the reverse factor, 1 ÷ 0.01.

What is 10 millimeters in decimeters?

10 mm = 0.1 dm.

Is this mm to dm converter accurate?

Yes. Both units are defined exactly in terms of SI units, so the conversion factor is exact; results are shown to 12 significant figures by default and you can change precision in the converter. Calculations run in your browser using the same tested engine that generated this page.

Millimeters to Decimeters Converter