Typical weekly weight gain from birth to age 2 on the WHO growth standard, in grams and ounces, and when a slow week matters.
Short answer: going by the WHO growth standard, a typical baby gains about 170 to 300 g (6 to 11 oz) a week in the first 3 months, about 110 to 120 g (4 oz) a week from 3 to 6 months, and about 50 to 75 g (2 to 2.5 oz) a week from 6 months to 2 years. Weight gain is fastest in the first weeks and slows steadily after that.
First, the dip. Most newborns lose weight in the first days, often 5 to 7% of birth weight and up to about 10%, and are back to birth weight by 10 to 14 days. Weekly gain is best counted from that point, not from the birth weight.
Weeks 2 to 4: the WHO median rises by about 265 g (9.3 oz) a week for girls and about 305 g (10.8 oz) a week for boys. This is the fastest growth of the whole first year.
Weeks 4 to 8: about 225 g (7.9 oz) a week for girls and 260 g (9.2 oz) for boys. Weeks 8 to 13: about 170 g (6.0 oz) for girls and 190 g (6.7 oz) for boys. By 3 months the median is 5.8 kg (12.9 lb) for girls and 6.4 kg (14.1 lb) for boys.
Months 3 to 6: about 110 g (3.9 oz) a week for girls and 120 g (4.2 oz) for boys, roughly half a kilo (1 lb) a month. The median at 6 months is 7.3 kg (16.1 lb) for girls and 7.9 kg (17.5 lb) for boys, a little more than double the birth weight.
Months 6 to 12: about 70 g (2.5 oz) a week from 6 to 9 months and about 55 g (1.9 oz) a week from 9 to 12 months. At 12 months the median is 9.0 kg (19.7 lb) for girls and 9.7 kg (21.3 lb) for boys, close to three times the birth weight.
From 1 to 2 years: about 50 g (1.8 oz) a week, or a little over 200 g a month, for both girls and boys. The median at 2 years is 11.5 kg (25.3 lb) for girls and 12.2 kg (26.8 lb) for boys.
These are the changes in the median curve, the middle of the chart. A baby on the 15th or the 85th percentile gains a bit less or a bit more each week and is just as typical. What matters is that your baby keeps roughly following their own percentile line.
Week-to-week numbers are noisy. A feed, a full diaper or a different scale can move a home weight by 50 to 100 g, which is a whole week of gain after 6 months. Compare weights a few weeks apart, ideally on the same scale.
When to talk to your pediatrician: weight loss of more than about 10% after birth, not being back to birth weight by about 2 weeks, few wet diapers, a baby too sleepy to feed, or a weight curve that falls across two of the main percentile lines over a few months.
To see your baby’s current weight percentile, use the free Growthling percentile calculator or the newborn weight chart by week. To see the curve, log each weigh-in in Growthling and it plots them on the WHO chart.
Numbers are differences between the WHO weight-for-age medians, from the WHO daily tables for the first 13 weeks and the monthly tables after that. Sources: WHO Child Growth Standards; CDC, “Use of World Health Organization and CDC Growth Charts for Children Aged 0–59 Months in the United States” (MMWR, 2010). This article is general information, not medical advice.
This article is for informational purposes only and is not a substitute for professional medical advice. Always consult your pediatrician about your child's growth and development.
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