3 months old baby boy how many hours have to sleep in a day

12-15. Please check my article on baby sleep for how this is broken up into night and day naps as well as how to establish sleep routines.

a 3 month old can sleep 4 hours in a day each nap being 1 hour . and at night can sleep 16 hours .

As Sonali has mentioned sleep routine is a must so as to feed routine both go in line and it will be easy for you too.