Ok, I understand what you are trying to do. You want to calculate the volume of an irregularly shaped object based on measurements (never ever going to be accurate, every egg is shaped differently) and then multiply it by known density (not even that is accurate unless you account for egg shell vs yolk vs whites vs air).
Why?! There are half a dozen ways to do what you're doing easier and more accurately. Do the water displacement. Go by weight. Anything. Unless you don't actually care at all about it being accurate. This is the most roundabout way of doing things.