:have almost four month old pedigree labrador pup.
Can u tell me how much it should weigh ?

It varies per dog. There are perameters for the breed but it depends on the level of exercise, whether he was the runt of the litter, and other factors.

If you're concerned about his weight it's a good idea to see your vet, he/she can actually examine the dog and determine whether his weight is healthy.

I have 2 black 2yr old labradors. One weighs 85 and the other weighs 90. They are both males and the vet said they are very healthy. The are slim muscular and fit.