Percentage in shrinkage of PLA and ABS Filament?

Can anyone give me a good estimate of how much I can expect both ABS and PLA to shrink when printed with? I am doing a project where I need to be very precise, and really need to try an calculate what the final size will be of particular parts once they are printed out. I know they both shrink to some degree, but I've heard that ABS shrinks more. Can anyone make any suggestions on what I could do to calculate shrinkage or provide me with some numbers?