Hi Axe, I saw your post but hadn't realised that any of the various sizes you were discussing were the "standard" large foil tray in which main courses are normally served. Perhaps because you mentioned 5 different tray sizes I jumped to the conclusion that they were all non-standard sizes (by which I mean not the sizes I'm used to seeing from my local takeaway)
Now armed with this new knowledge and in the interests of science I've just poured 850ml of water into my 20" Meyer HT+ frying pan to see how full it would be. Right up to the brim was the answer!