Samantha is almost 8 weeks old and she is having 4 oz. every 2-3 hours (mostly every 2 hours). Sometimes she eats way more--the other morning she had 8 oz. within 2 hours, but she had also slept 5 hours during the night. At first, I didn't know how much she was getting because I breastfed for about a month. She was always hungry though. She still loves to eat, but is definitely satisfied after a feeding now instead of irritable. But, I think if there were 10 oz. in the bottle, she would keep on chugging!