How much coolant do you need to do a flush?

[Bateman]

How much coolant does it take to fill an empty Boxster after a flush to its normal level again? Just had one done and I just wanna double check to make sure I'm not being overcharged for the coolant (which I realize is fairly pricey).

Thanks

[kabel]

Have a look here, a quick search using "coolant" & "capacity" turned up this:

coolant flush...step by step with pics