You're right cazza1, but it's not as bad as you might think. Egg quantities have a certain amount of leeway. I buy eggs from a local farm and they come unsorted in varying sizes but the average weight (unshelled) is 54g. I worked that out when making a huge wedding cake using about 30 eggs... So if I work out egg quantities by weight I can usually get it very close by selecting a larger or smaller egg for the last one... Also with most cake recipes if you're a bit under, it's OK to make up the egg weight with milk or water. Yes I'm, a bit OCD about it...