turtles

Ihave 2 red ear turtiles How can I tell if male or female?

[seattlemom2plus]

I found this on WikiHow:

"Look at the bottom or underbelly of the turtle's shell. If the plastron (bottom shell) is convex, goes out, it's probably a female. If its bottom shell is concave (rounded) or goes in toward the inside of the body, then the turtle is most likely a male.[8] The reasoning behind this is that the female's convex plastron provides more room for eggs, while the male's concave plastron fits better over the female's when mating."