The only way to accurately gauge what your baby is taking while breastfeeding is to use a specially designed scale. These scales (such as the Medela BabyWeigh scale) are accurate to within +/- 0.1 ounces and are available for rent in most areas. By performing a “test weigh” with one of these scales before and after each feeding, you can accurately measure the amount of milk your baby is taking at each feed. If your baby is gaining weight (five to eight ounces per week for the first few months) without any additional supplements, then your milk supply is fine. If your baby is having difficulty gaining weight, then a scale will help you assess what your baby's actual intake at the breast is.