How long do astronauts stay in space?

About 6 months at a time and in the Russian program 1 year
It depends on the mission actually. It can be weeks or months even a year! However, the problem is when astronauts goes back on Earth. Getting used to gravity again which would take a while depending on how long they stayed in space.
This will depend on how long the space mission is planned for.
It depends on how long their mission is. Normally ranging from 10 days up to a few months but not much longer than that because staying in an enviroment without gravity for too long can weaken the astronaut's muscles. It also depends on how much oxygen and food is taken into space with the space ship.