Conversion formula

The conversion factor from millimeters to kilometers is 1.0E-6, which means that 1 millimeter is equal to 1.0E-6 kilometers:

1 mm = 1.0E-6 km

To convert 421 millimeters into kilometers we have to multiply 421 by the conversion factor in order to get the length amount from millimeters to kilometers. We can also form a simple proportion to calculate the result:

1 mm → 1.0E-6 km

421 mm → L_(km)

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

L_(km) = 421 mm × 1.0E-6 km

L_(km) = 0.000421 km

The final result is:

421 mm → 0.000421 km

We conclude that 421 millimeters is equivalent to 0.000421 kilometers:

421 millimeters = 0.000421 kilometers

Alternative conversion

We can also convert by utilizing the inverse value of the conversion factor. In this case 1 kilometer is equal to 2375.296912114 × 421 millimeters.

Another way is saying that 421 millimeters is equal to 1 ÷ 2375.296912114 kilometers.

Approximate result

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

421 mm ≅ 0 km

An alternative is also that one kilometer is approximately two thousand three hundred seventy-five point two nine seven times four hundred twenty-one millimeters.

Conversion table

millimeters to kilometers chart

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