Good morning to everyone who has commented or emojied (is that a word) my OP. And thank you for your varying replies, correct, off topic or whatever.
In reply to terryq's reply, I have just put my measuring jug on my kitchen digital scales and put water in until 620 gm. It came up to the 600ml line. So yes, my lab standard coffee jug is incorrect. I apologise for any sleepless night anyone may have had worrying about my so called trolling, I am NOT one of those, and cannot compete in that subject with the several other who frequent this forum.
Once again, good morning and thanks for your concern.