How can you tell a male red-eared slider turtle from a female?

Question

I have 2 red-eared slider turtles. I have no idea what sex they are. Is there an easy way to tell who is what?

Answer 1

Until they reach sexual maturity it can be difficult to tell but as adults:
Males have much longer claws.
Males generally dont get as big as females.
Females "red ear" is not as brightly colored.
Females tail is fatter.
Males anus is further out on tail.
Males tail is longer.

Answer 2

look at the bellies if it curves in like a bowl it is a male (sits on top of female during sex) the females stomach is flat