Dylan, eggs vary in shape considerably. They can be almost spherical, almost ovoid and certainly are usually not symmetrical on all axes.

The easiest way is to measure it by displacement. Get a graduated beaker or measuring cup, fill partially with water and take a good reading. Then submerge the egg and take a new reading. The difference in water level is the volume of the egg.

If you really want a formula for an abstract idealized egg, take a look at http://mathworld.wolfram.com/Ovoid.html. You could try integrating the circular cross-sections using Lockwood's description of an ovoid. Or you may find "Moss's egg" more appropriate: http://mathworld.wolfram.com/MosssEgg.html

Cheers,
Stephen La Rocque.

Dylan,

If you are looking for the volume with regard to cooking there is a page that converts the volume of an egg to tablespoons.

Penny