The weight of a 4-month-old baby generally reaches twice its weight at birth. Monitoring your baby's weight development is very important to help find out if your baby is growing and developing properly. At the age of 4 months, the baby has a good development in terms of body size, physical abilities, and sensitivity to the surrounding environment. At this age, babies can begin to show expressions, such as smiling, laughing, trying to talk, and start putting their hands and feet or other objects in the mouth. Ideal Size for Baby Weight 4 Months At the age of 4 months, the baby will experience a surge in weight reaching 0.5 kilograms of body weight at the age of 3 months. Although the increase in baby weight is generally the same 4 months, but baby boys generally have a greater weight and length than female babies. Weight of babies 4 months with male sex, on average ranges between 5.6-8.6 kilograms and has a length between 60 to 67.8 centimeters (cm). Meanwhile, babies weighi