The Kuiper belt is a region of icy bodies beyond Neptune. It's not a well-defined edge, but generally considered to extend from about 30 Astronomical Units (AU) to 50 AU from the Sun.

Here's the conversion to kilometers:

* 1 AU = 149,597,870.7 kilometers

So, the Kuiper belt is roughly 4,487,936,121 kilometers (30 AU) to 7,479,893,535 kilometers (50 AU) from the Sun.