I, being of curious disposition, looked up the size of schooners last night. It turns out that a Geordie schooner is 284ml, a normal UK schooner is 379ml. In Australia, excepting South Australia, a schooner is 425ml. If you happen to be thirsty in South Australia, a schooner is 285ml. Elsewhere in Aus, this is called a pot, though it's a middy in NSW and W Aus. If you ask for a schooner of beer you may get 375ml of liquid and 50ml froth. If you're really thirsty, you'd be better off somewhere like Canada, where it's 946ml (2 US pints) but it's usually served in a tankard-style glass. In the US, schooner isn't a size, it's a shape, and it can be anywhere between 532ml to 946ml.
No need to thank me....