The right age for a kid to stay home alone is between 11 to 12 years of age.
However it's not just age that determines if the kid is able to stay home alone but also the maturity of the kid and how trusting the kid is.
Also some states have laws that say when you can legally leave a kid home alone so check with your local laws.
However according to experts they say it's okay to leave most children home alone for at least an hour once they reach 10 years of age.
Once the child reaches 13 to 15 years old then they can be left home alone for longer than an hour and usually for 8 hours or longer.
If the child is under 13 then you should have someone check on them and make sure they know how to get help when needed and to never open the door to a stranger.