Literature Fairy is right. A year is right. My son weaned himself from formula when he was 9m. He wouldn't take it.(he had formula from 3 1/2m-9m) My doctor told me to go ahead with cows milk because my son was in the 100th percentile from birth. My son will be 3 in August and he is 3 ft 6 inches tall and weighs about 60 lbs. The best recommendation is also as Literature Fairy said, it has to be full fat milk!