Overstaying fine

How much is the overstaying fine after work visa expires? Is it related to time? I mean is the a ratio of increased fine in relation to the overstaying period?

It is on a per day basis.  Beyond a certain period, it ramps up.  And also, you can't leave until you pay.  Trouble with future visas too.   So it's not just the money - the hassle is just isn't worth overstaying.