By 3 months of age, most babies double their birth weight and gain approximately 1.5 to 2 pounds per month (or 0.5 to 1 ounce per day). A baby weighing 7.5 pounds at birth, for example, would typically reach 15 pounds by 3 months.
However, weight gain varies considerably among healthy babies depending on genetics, feeding method (breast or formula), and individual growth patterns. Some babies gain faster or slower than average while remaining completely healthy. Exclusively breastfed babies sometimes gain weight at slightly different rates than formula-fed babies, particularly after 3 months.
What matters most is consistent, steady growth rather than hitting a specific number. Your pediatrician tracks your baby's weight on growth charts and monitors the trajectory—whether your baby is following their own growth curve matters more than matching an average. Regular check-ups at 1 month, 2 months, and 3-4 months allow your doctor to assess whether weight gain is adequate and rule out feeding or health concerns.
Signs of healthy weight gain include the baby having adequate wet diapers (6+ daily after the first few days), regular bowel movements, seeming satisfied after feeds, and reaching developmental milestones. If you have concerns about your baby's weight gain, discuss them with your pediatrician rather than relying on general guidelines alone, as they can evaluate your specific baby's health and feeding circumstances.