It all depends on species. Some species, such as the red-eyed tree frog, leopard frog, and other common medium-sized species, egg to adult, eggs hatch at different times depending on species, ( although the lowest I know about is hatching a week after fertilization) and then tadpole to froglet for those species is about 7-9 weeks, then froglet to adult is I'm not sure, but I think it's a couple of months. For bullfrogs, you will probably be waiting a while, my friend. I don't know how long it takes them to hatch, but I know that these huge tads take up to 2 years to develop into a froglet. And then I don't know how long it takes them to reach adulthood.