I really have no idea....I BF and its hard to tell. I usually feed him on demand but it works out to be about 2-3 hours. Just this week he started to give me a 4 hour stretch at night. I have pumped a bit and had people feed him if I go out. My mom said he was still hungry after 3 ounces. So I am guessing between 3-4? I was wondering the same thing because I am going out to eat tonight and not sure how much to leave.
My son was 9 pounds, 6 ounces at birth. His next appt. is Wednesday so we'll see about his weight gain.