Since we maintain that the olives of today are smaller than in times of chazal, how many olives would one need to eat to make a shiur requiring an al-haeitz?
It depends on the size of the olive. There are 15(!) differant official sizes to olives ranging from 45 per pound to 220 per pound. (Not all olives were created equal…) In general, the size of a kzazis is the size of an Israeli matchbox, or the size of a gold ball, or half an egg. It is also important to remember that the pit of the olive is not eaten, therefore you would need to eat half an eggs worth of olive of olive meat to say al -haeitz.