You wnt to know that for how much time can you leave your Labrador alone?

Labradors can be left alone for long periods of time. You do need to take into consideration their need to go to the bathroom. I would suggest any more than 5 hours without someone coming to let the dog out. If the dog is young i would recommend crating to make sure that the dog dog not start destroying your furniture in its boredom. Put some chew toys in the crate with your dog.