I could not give you an exact amount of fliud and there would be a difference on different cars, bigger master cylinders, wheel cylinders, calipers and so on.
If you want to stop wearing out those legs trying to bleed a system just gravity bleed it. Make sure everything is clean, tight,rear brakes adjusted & no leaks and fill the master cylinder up. Just pump the pedal one or two times then open all bleeders and let the fluid do the work. Just watch the level of the master cylinder keeping it full and watch each bleeder valve untill a steady stream of fluid comeing out. Then you should be able to have someone pump the pedal and you should only have to open the bleeders once. If you still get a spongy pedal or air then you have a leak somewhere.
Gravity bleeding allows you to work on other things while air is being forced out and not wear out your leg. It's been many years since I worked a pedal to bleed brakes.