Your newborn may drink anywhere from 2-3 fluid ounces of formula about every three hours. In general, your baby will take in what he needs to meet his body's demands. So don't be too concerned about fixed amounts. Instead, feed him when he's hungry. He'll let you know when he's finished. If he drinks a bottle and still acts hungry, he probably is. Offer him an extra ounce.
Most babies do fine with 3-4 fluid ounces per feeding during the first couple months. Increase by about 1 ounce a month until he is drinking up to about 6-8 fluid ounces at 6 months of age.