About 70 pounds for a male.
There are "monsters" out there, that are about double a normal Lab's weight. The neighbor's black monster is still growing, and is nearly 140 pounds. He's not fat at all, kind of skinny actually. His brother was visiting and is exactly the same size. He's got a head on him that's about 15" long, and the teeth are huge! He's a great dog, but keeps coming into my yard, where Molly still makes him miserable. She doesn't want him in her yard, and harrasses him until he leaves. King barely responds to him being there, and usually just ignores him. Last week, he growled at Molly, and King ran up and gave him the eye, and over on his back he went.
King and Molly together don't weigh more than 125 pounds. It's pretty funny to see Molly chase him around the yard, "punching" him the entire time.