[alkonaut]

Depends on whether you mean 20mins on a bus/commuter train or 20min commute door-to-door. 20min on bus/commuter train easily cuts rents down by a lot, but such a commute is likely 40min in total if you include walking to the bus/train and walking from the train to the office. 5k is really low and likely only gets you a room or a small 1 room apt at the outskirts of the 20min commute.

Btw. I made an experiment that shows approximate commute times on weeekday morning (including walks to stations but no walk from Sthlm Central Station). http://commutemap.azurewebsites.net/

Edit: note the green "islands" of 20minute commute that extend along the commuter train lines.