I'm wondering what this question is for? If it is for a babysitter, or daycare? Also, how old is your baby? The intake changes and your doctor should have the "average".
For the babysitter, you can always guess and then have some back up if the baby sucks it down. You can also feed your baby a bottle and see how much he/she eats to get an idea of where to start.
My son was born at 8lbs 12oz. At 10 weeks we started with 4 ounces. Sometimes he would take it all, sometimes less, but I tried to get the daycare to NOT throw away the uneaten milk like they do with formula, and to use it in the next bottle. That daycare thought he needed more and bumped him up to 6 oz one day!! That was a huge jump and my son took it, but then spit it all up. I hated that waste. I also changed daycares. As he got bigger, and as he decreased in the number of feedings, I would increase the ounces.
I personally didn't feed on demand, or have the daycare do so as I needed to know how much milk to bring with me, and how often to pump. If I pumped before picking him up and he was hungry, or wouldn't pump and he was just fed, it made it too difficult. Plus, I just believed in schedules and my son thrived that way. Plus, each of his daycare classes from about 1 year on have schedules, so it helped with the transition. Good luck, and let me know if you need any further information.
He never seemed to be getting the "recommended" amount, but I don't really know how much he was getting from me either. He has always been "well fed" and was about 23.5 pounds at his 1 year checkup.