Hi! Thanks

The females tympanum is about the same size as their eye and the males tympanum is larger. Here are some pictures... (Not my pictures. Just for examples)

Male...


Female...


A definite way to tell is when they croak,..then you have a male. Males can tend to have a more yellow hue under their chins in a regularly colored bullfrog. Of course, in an albino this is not helpful.