Normal baby weight by age for boys and girls from birth to 5 years (WHO) — average and healthy range in kg or lb, plus where your baby’s weight falls.
How much should my baby weigh?
Healthy babies come in many sizes. The WHO Child Growth Standards show how healthy breastfed children grow; the normal range runs roughly from the 3rd to the 97th percentile. What matters most is that your baby keeps growing along a steady curve.
Age
Boys: average (normal range)
Girls: average (normal range)
Birth
3.3 kg (2.5–4.4)
3.2 kg (2.4–4.2)
3 months
6.4 kg (5.1–7.9)
5.8 kg (4.6–7.4)
6 months
7.9 kg (6.4–9.7)
7.3 kg (5.8–9.2)
9 months
8.9 kg (7.2–10.9)
8.2 kg (6.6–10.4)
12 months
9.6 kg (7.8–11.8)
8.9 kg (7.1–11.3)
2 years
12.2 kg (9.8–15.1)
11.5 kg (9.2–14.6)
3 years
14.3 kg (11.4–18.0)
13.9 kg (11.0–17.8)
5 years
18.3 kg (14.3–23.8)
18.2 kg (14.0–24.4)
Values are WHO medians with the 3rd–97th percentile range, rounded. Babies usually lose up to 7–10% of birth weight in the first days and regain it by about 2 weeks; most double their birth weight by 4–5 months and triple it by 1 year. For a detailed percentile with length and head size, use the growth percentile calculator.
Frequently asked questions
What is the normal weight of a 6-month-old baby?
For boys the average is about 7.9 kg (range 6.4–9.7 kg); for girls about 7.3 kg (5.8–9.2 kg), using WHO standards.
Is my baby underweight?
A weight below the 3rd percentile, or a weight that falls across two percentile lines, should be checked by your paediatrician.
Do breastfed babies gain weight differently?
Breastfed babies often gain faster in the first months and more slowly later. The WHO standards are based on breastfed babies, so they fit this pattern well.