A.W.
Hi A.!
I recently had my daughter's one year dr. appt. and asked him this same question. He said no more than 24 oz. of whole milk a day. I typically give my daughter a sippy cup of milk with breakfast, lunch, and afternoon snack (totaling around 18-20 oz., on average) and then a sippy cup of water with dinner. It seems to be working well for us.
Good luck!