Conversion formula

The conversion factor from millimeters to decimeters is 0.01, which means that 1 millimeter is equal to 0.01 decimeters:

1 mm = 0.01 dm

To convert 0.4 millimeters into decimeters we have to multiply 0.4 by the conversion factor in order to get the length amount from millimeters to decimeters. We can also form a simple proportion to calculate the result:

1 mm → 0.01 dm

0.4 mm → L_(dm)

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

L_(dm) = 0.4 mm × 0.01 dm

L_(dm) = 0.004 dm

The final result is:

0.4 mm → 0.004 dm

We conclude that 0.4 millimeters is equivalent to 0.004 decimeters:

0.4 millimeters = 0.004 decimeters

Alternative conversion

We can also convert by utilizing the inverse value of the conversion factor. In this case 1 decimeter is equal to 250 × 0.4 millimeters.

Another way is saying that 0.4 millimeters is equal to 1 ÷ 250 decimeters.

Approximate result

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

0.4 mm ≅ 0.004 dm

An alternative is also that one decimeter is approximately two hundred fifty times zero point four millimeters.

Conversion table

millimeters to decimeters chart

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