Conversion formula

The conversion factor from centimeters to millimeters is 10, which means that 1 centimeter is equal to 10 millimeters:

1 cm = 10 mm

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

1 cm → 10 mm

0.4 cm → L_(mm)

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

L_(mm) = 0.4 cm × 10 mm

L_(mm) = 4 mm

The final result is:

0.4 cm → 4 mm

We conclude that 0.4 centimeters is equivalent to 4 millimeters:

0.4 centimeters = 4 millimeters

Alternative conversion

We can also convert by utilizing the inverse value of the conversion factor. In this case 1 millimeter is equal to 0.25 × 0.4 centimeters.

Another way is saying that 0.4 centimeters is equal to 1 ÷ 0.25 millimeters.

Approximate result

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

0.4 cm ≅ 4 mm

An alternative is also that one millimeter is approximately zero point two five times zero point four centimeters.

Conversion table

centimeters to millimeters chart

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