421 millimeters in kilometers

Conversion formula
How to convert 421 millimeters to kilometers?

We know (by definition) that: $1\mathrm{mm}=1e-06\mathrm{km}$

We can set up a proportion to solve for the number of kilometers.

Now, we cross multiply to solve for our unknown $x$:

Conclusion: 421 ⁢ mm = 0.000421 ⁢ km

Conversion in the opposite direction

The inverse of the conversion factor is that 1 kilometer is equal to 2375.29691211401 times 421 millimeters.

It can also be expressed as: 421 millimeters is equal to $\frac{1}{\mathrm{2375.29691211401}}$ kilometers.

Approximation

An approximate numerical result would be: four hundred and twenty-one millimeters is about zero kilometers, or alternatively, a kilometer is about two thousand, three hundred and seventy-five point three zero times four hundred and twenty-one millimeters.