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 420 millimeters into decimeters we have to multiply 420 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

420 mm → L_(dm)

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

L_(dm) = 420 mm × 0.01 dm

L_(dm) = 4.2 dm

The final result is:

420 mm → 4.2 dm

We conclude that 420 millimeters is equivalent to 4.2 decimeters:

420 millimeters = 4.2 decimeters

Alternative conversion

We can also convert by utilizing the inverse value of the conversion factor. In this case 1 decimeter is equal to 0.23809523809524 × 420 millimeters.

Another way is saying that 420 millimeters is equal to 1 ÷ 0.23809523809524 decimeters.

Approximate result

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

420 mm ≅ 4.2 dm

An alternative is also that one decimeter is approximately zero point two three eight times four hundred twenty 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