How many millimeters are in 1 decimeter?

One decimeter contains exactly 100 millimeters. Since 1 dm = 10 cm and 1 cm = 10 mm, multiply 10 by 10.

How do I convert decimeters to millimeters?

Multiply by 100 or move the decimal point two places to the right. For example, 3.5 dm = 350 mm.

When would I use decimeters instead of millimeters?

Almost never for linear measurement. Millimeters are the standard in engineering, manufacturing, and medicine. The decimeter's main role is defining the liter (1 dm3 = 1,000 mL = 1 L).

Decimeters to Millimeters (dm to mm) Converter

1 dm = 100 mm

1 Decimeter equals 100 Millimeters (1 dm = 100 mm). Convert Decimeters to Millimeters with formula, table, and examples.

One decimeter equals exactly 100 millimeters. This is a straightforward metric conversion, moving two steps down the prefix ladder from deci- (tenth of a meter) to milli- (thousandth of a meter). Both units are commonly used, though millimeters dominate in engineering and manufacturing.

How to Convert Decimeters to Millimeters

mm = dm × 100

Multiply the value in Decimeters by 100

Take your value in Decimeters
Multiply by 100
Read the result in Millimeters

Common Decimeters to Millimeters Conversions

Decimeters (dm)	Millimeters (mm)	Status
0.01 dm	1 mm
0.05 dm	5 mm
0.1 dm	10 mm
0.25 dm	25 mm
0.5 dm	50 mm
1 dm	100 mm
2 dm	200 mm
5 dm	500 mm
10 dm	1,000 mm
20 dm	2,000 mm
50 dm	5,000 mm
100 dm	10,000 mm
200 dm	20,000 mm
500 dm	50,000 mm
1,000 dm	100,000 mm

Good to Know About Decimeters to Millimeters Conversion

Engineers worldwide specify parts in millimeters. Volume is measured in liters (defined by the dm³). The decimeter bridges these two worlds but is invisible in both: nobody says 'hand me the 0.1 dm wrench' or 'pour me 10 dm³ of water.'

Decimeters to Millimeters: What You Need to Know

A decimeter (10 cm) contains exactly 100 mm. A standard credit card at 85.6 mm is 0.856 dm wide. Engineering drawings specify tolerances in millimeters, not decimeters. A 10 mm wrench is 0.1 dm long. The millimeter's dominance in precision work makes the decimeter unnecessary for technical applications.

What is a Decimeter? dm

One tenth of a meter, or 10 centimeters. Used in some European countries for everyday measurements and in education.

Metric European education everyday measurement

Learn more about Decimeter →

What is a Millimeter? mm

A metric unit of length equal to one thousandth of a meter. Used in engineering, manufacturing, and precise measurements.

Metric engineering manufacturing rainfall

Learn more about Millimeter →

Going the other way? Use our Millimeters to Decimeters converter.

Decimeters to Millimeters FAQ

One decimeter contains exactly 100 millimeters. Since 1 dm = 10 cm and 1 cm = 10 mm, multiply 10 by 10.
Multiply by 100 or move the decimal point two places to the right. For example, 3.5 dm = 350 mm.
Almost never for linear measurement. Millimeters are the standard in engineering, manufacturing, and medicine. The decimeter's main role is defining the liter (1 dm³ = 1,000 mL = 1 L).

Non-Frequently Asked Questions About Decimeters to Millimeters

Questions nobody should ask - but someone did.

A decimeter is exactly 100 mm. It is not pretending - it genuinely defines the liter (1 dm³ = 1,000 mL). Without the decimeter, the liter would lack its elegant cubic definition. The millimeter may be more popular, but the decimeter has better connections.
Engineers need precision. Millimeters give fine resolution for tolerances (0.1 mm, 0.01 mm). Decimeters are too coarse - saying '±0.001 dm tolerance' is just '±0.1 mm' with extra steps. Engineers value efficiency over prefix variety.
A credit card is about 0.76 mm thick. A decimeter is 100 mm. So about 132 credit cards stacked up equals one decimeter. If you have 132 credit cards, you have either a very diverse wallet or a very serious problem.