Instructions
Examine the turtle's tail. If you can, pull it out a bit for a better look. The males will have a longer and thicker tail, while females have shorter and thinner tails.
Turn the turtle on its back and pull the tail out. Note the cloacal opening (the opening that serves for reproduction as well as emptying out solid and liquid waste). The male's opening is farther down on its tail, while the female's is closer to its shell.
Note the underside of the turtle. A male will often have a concave under shell in order to make it easier for him to mount and mate with a female turtle.
Take note of the turtle's claws and nails. A male has long and thick nails (which are used to stroke the female before mating); a female has shorter and thinner nails.
How to Tell a Male From a Female Painted Turtle
Painted turtles, or Chrysemys pictas, are a species of turtle in North America (more specifically southern Canada, the United States Northern Mexico). They live in bodies of water that have a muddy bottom and eat worms, fish and frogs. They add vegetation to their diet by eating small leaves. Unlike other types of turtles, the gender of painted turtles can be readily identified in mature turtles. Their features are less apparent in young turtles.