In km/sec, how fast is the universe expanding?
The expansion of universe varies as distance increases as per Hubble law.
Recessional velocity= H0 x r
where H0= hubble constant
r= recessional velocity.
Hubble constant is 73 Km/second/mega parsecond.
so to find expansion rate you have to multiply with Hubble constant with distance to object.
picture about space.com.