It depends on the temperature, if its in the full sun and its hot, they can die very quickly. If its chilly or not very hot when they flip over the can stay alive for hours. Just know the sooner they are turned over the better. Usually they can find a way to turn themselves up right on their own and if they are young, its good to let them try to do it on their own under your watch. They can teach them selves how to do it this way. But usually if they have a hiding enclosure they will go inside it and not be tempted to climb up and fall over.