Quote Originally Posted by ProZachNation
Is there some sort of equation using the size and strength of a magnet to determine the size of its magnetic field?
You would be looking for Maxwell's equations. I looked around for the best link and found that Wikipedia has a pretty good.

Understand though, that magnets do not side step nature's laws. Not only do they follow those laws, they were one of the early things that helped man discover those laws.

The equations that describe how electro-magnetic fields interact to produce force are extremely well understood. They are used everyday to compute how much force a motor will generate and, in reverse, how much electro-motive force will be generated with a generator is driven. The difference between the energy put into the device and the useful energy out of either device is the heat and deformation loss to friction and the hysteresis loss.