The Average Weight and Length of 6-Month-Olds

Throughout infancy, your baby will grow at varying rates, says Dr. Anil Pradhan, a pediatrician in Bradford, Pennsylvania. Normal weight and height of a 6-month-old can be determined by a number of factors. Understanding how growth charts work and the factors that affect your baby’s growth will help assure you that your baby’s growth falls within normal limits.

Your Baby's Growth

From the moment of conception, factors affect the size of your baby. While in the womb, genetics and what your eat or drink affects the growth of your baby, according to the Illinois Early Learning Project. After birth, growth depends on genetics, the type of food and drink your baby gets, her overall health and the quality of the her medical care. How well your baby produces and uses hormones may also affect how she grows, according to Each baby grows at a different pace. On average, your baby should put on approximately 1.25 lbs. in her sixth month and grow between 0.5 and 1 inch, according to the Cincinnati Children’s Hospital.

Growth Charts

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Growth charts allow your doctor to chart and track your baby’s growth and development. The growth charts provide national height and weight averages for babies of the same age. A baby of normal weight and height should fall on the growth chart between the 5th percentile and the 95th percentile, according to Pradhan. To weigh a baby, the nurse will strip the baby completely. For your baby’s height, the nurse will measure from the top of your baby’s head to the bottom of her heel. A 6-month-old girl should weigh between 12.9 and 19 lbs. and stand between 24 to 27.25 inches tall, while a 6-month-old boy should weight between 14.4 and 21.2 lbs. and stand between 24.8 and 28.25 inches tall, according to weight and length for age growth charts provided by the Centers for Disease Control and Prevention.

Chubby Baby

Even if your baby falls above the 95th percentile on growth charts, do not withhold food or drink from him. For proper growth and development, your baby needs proper nutrition, including fat, according to Instead of limiting your baby’s food intake, make sure he gets nutritious foods and drinks. If you give him juice, limit it to 4 oz. a day of unsweetened fruit juice. Instead of feeding your baby snacks and desserts high in “empty” calories, give him pureed fruits and vegetables without added sugar. Finally, always encourage your baby to play actively and move around as much as possible.

When To Be Concerned

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Be concerned if your baby’s percentile changes significantly. If a large drop or increase in percentile occurs, your doctor will run tests to determine the cause, Pradhan says. The doctor may also run tests if your baby’s percentiles fall above 95 percent or below 5 percent, especially if the parents' sizes do not reflect the same extremes.