What is the average baby weight by month?
Medically reviewed by Carissa Stephens, R.N., CCRN, CPN — Written by MaryAnn De Pietro, CRT — Updated on June 19, 2024
Children develop at different paces, but the average birth weight of a full-term male baby is 3.3 kilograms (kg) and 3.2 kg for a female. Growth charts can provide a guide to the average weight of a baby.
- Average birth weight: 3.3 kg for males and 3.2 kg for females.
- Most babies double their birth weight by 4 months.
- Weight variations are normal; look at overall growth.
Average baby weights
According to the World Health Organization (WHO), the average birth weight of a full-term male baby is 7 pounds (lb) 6 ounces (oz), or 3.3 kilograms (kg). The average birth weight for female babies is 7 lb 2 oz, or 3.2 kg. The chart below details average weights by age:
| Baby age | Female (50th percentile) | Male (50th percentile) |
|---|---|---|
| Birth | 7 lb 2 oz (3.2 kg) | 7 lb 6 oz (3.3 kg) |
| 1 month | 9 lb 4 oz (4.2 kg) | 9 lb 14 oz (4.5 kg) |
| 2 months | 11 lb 5 oz (5.1 kg) | 12 lb 4 oz (5.6 kg) |
| 12 months | 19 lb 12 oz (8.9 kg) | 21 lb 4 oz (9.6 kg) |
What affects baby weight?
Weight alone doesn’t tell the whole story in a baby’s health. Factors influencing baby weight include:
- Sex: Male newborns typically weigh more.
- Nutrition: Breastfed babies gain weight slower than formula-fed infants initially, but both follow similar patterns over time.
- Prematurity: Premature babies may gain weight slower but catch up later.
Summary
Knowing the average weights can help gauge a baby’s growth, but always consult a healthcare provider to discuss any concerns.
