## Conversion formula

The conversion factor from decimeters to millimeters is 100, which means that 1 decimeter is equal to 100 millimeters:

1 dm = 100 mm

To convert 4 decimeters into millimeters we have to multiply 4 by the conversion factor in order to get the length amount from decimeters to millimeters. We can also form a simple proportion to calculate the result:

1 dm → 100 mm

4 dm → L(mm)

Solve the above proportion to obtain the length L in millimeters:

L(mm) = 4 dm × 100 mm

L(mm) = 400 mm

The final result is:

4 dm → 400 mm

We conclude that 4 decimeters is equivalent to 400 millimeters:

4 decimeters = 400 millimeters

## Alternative conversion

We can also convert by utilizing the inverse value of the conversion factor. In this case 1 millimeter is equal to 0.0025 × 4 decimeters.

Another way is saying that 4 decimeters is equal to 1 ÷ 0.0025 millimeters.

## Approximate result

For practical purposes we can round our final result to an approximate numerical value. We can say that four decimeters is approximately four hundred millimeters:

4 dm ≅ 400 mm

An alternative is also that one millimeter is approximately zero point zero zero three times four decimeters.

## Conversion table

### decimeters to millimeters chart

For quick reference purposes, below is the conversion table you can use to convert from decimeters to millimeters

decimeters (dm) millimeters (mm)
5 decimeters 500 millimeters
6 decimeters 600 millimeters
7 decimeters 700 millimeters
8 decimeters 800 millimeters
9 decimeters 900 millimeters
10 decimeters 1000 millimeters
11 decimeters 1100 millimeters
12 decimeters 1200 millimeters
13 decimeters 1300 millimeters
14 decimeters 1400 millimeters