Newborn weight chart by week

WHO weight percentiles for newborn girls and boys at every week from birth to 13 weeks, in kg with lb for the median. For older babies, see the baby weight chart by month.

Key numbers

At birth, the WHO median weight is 3.2 kg (7.1 lb) for girls and 3.3 kg (7.4 lb) for boys.
At 4 weeks, the median is 4.1 kg (9.0 lb) for girls and 4.4 kg (9.6 lb) for boys.
At 13 weeks (about 3 months), the median is 5.8 kg (12.9 lb) for girls and 6.4 kg (14.0 lb) for boys.
Between 2 and 13 weeks, median weight goes up by about 206 g a week for girls and 238 g a week for boys.

Girls: weight by week (WHO)

Values in kg at each percentile. Median also in lb.

Age	3th	15th	Median	85th	97th	Median (lb)
Birth	2.44	2.78	3.23	3.73	4.17	7.1
1 week	2.51	2.86	3.34	3.87	4.35	7.4
2 weeks	2.70	3.07	3.57	4.13	4.64	7.9
3 weeks	2.92	3.31	3.84	4.43	4.96	8.5
4 weeks	3.14	3.55	4.10	4.72	5.28	9.0
5 weeks	3.35	3.77	4.35	5.00	5.58	9.6
6 weeks	3.54	3.98	4.58	5.25	5.87	10.1
7 weeks	3.72	4.18	4.79	5.49	6.13	10.6
8 weeks	3.89	4.36	5.00	5.72	6.37	11.0
9 weeks	4.05	4.53	5.18	5.92	6.60	11.4
10 weeks	4.20	4.69	5.36	6.12	6.81	11.8
11 weeks	4.34	4.84	5.53	6.31	7.02	12.2
12 weeks	4.47	4.98	5.69	6.49	7.21	12.5
13 weeks	4.60	5.12	5.84	6.65	7.40	12.9

Boys: weight by week (WHO)

Values in kg at each percentile. Median also in lb.

Age	3th	15th	Median	85th	97th	Median (lb)
Birth	2.51	2.86	3.35	3.88	4.35	7.4
1 week	2.63	2.99	3.49	4.04	4.54	7.7
2 weeks	2.85	3.23	3.75	4.33	4.85	8.3
3 weeks	3.10	3.51	4.06	4.67	5.22	9.0
4 weeks	3.36	3.79	4.37	5.01	5.59	9.6
5 weeks	3.61	4.05	4.66	5.33	5.93	10.3
6 weeks	3.84	4.30	4.93	5.63	6.25	10.9
7 weeks	4.05	4.53	5.18	5.90	6.55	11.4
8 weeks	4.25	4.75	5.41	6.15	6.82	11.9
9 weeks	4.44	4.95	5.63	6.39	7.07	12.4
10 weeks	4.62	5.14	5.83	6.61	7.30	12.9
11 weeks	4.78	5.31	6.02	6.81	7.52	13.3
12 weeks	4.94	5.48	6.20	7.00	7.72	13.7
13 weeks	5.09	5.63	6.37	7.18	7.91	14.0

The first two weeks

Almost all newborns lose weight in the first days as they pass fluid and meconium and feeding gets going. A loss of around 5 to 7% is common, and up to about 10% can still be normal. Most babies are back to birth weight by 10 to 14 days.

The WHO table above describes typical growth from birth and does not show this early dip, so a baby a few days old will often plot below their birth percentile. Compare from about two weeks on, and tell your pediatrician if your baby loses more than about 10%, is not back to birth weight by two weeks, has few wet diapers, or seems too sleepy to feed.

Find your baby’s weight percentile (centile)

Enter the date of birth and today’s weight. The calculator uses the WHO standard for your baby’s exact age and shows the weight percentile and z-score. In the UK and Ireland the percentile is called the centile; from 2 weeks it matches the UK-WHO chart in the Red Book.

Sex

Units

Date of birth Date measured Weight (kg) Length (cm) Head circumference (cm)

Chart

Enter a date of birth and at least one measurement to see the percentile.

Common questions

How much weight do newborns lose after birth?

Most newborns lose some weight in the first days, often around 5 to 7% of birth weight and up to about 10%. Pediatricians watch more closely when the loss goes beyond about 10%.

When should a baby be back to birth weight?

Most babies are back to their birth weight by about 10 to 14 days. Your pediatrician will usually check weight at the first visits to confirm this.

How much should a newborn gain each week?

Going by the WHO medians, about 206 g a week for girls and 238 g a week for boys between 2 and 13 weeks. Individual babies vary, and the trend over several weeks matters more than one week.

Where do these numbers come from?

From the WHO Child Growth Standards, which the CDC recommends for children under 2. The table uses the WHO daily LMS tables at each whole week from birth to 13 weeks.

Is this the same as the UK-WHO or Irish centile chart?

From 2 weeks on, yes. A centile is the same as a percentile, and the UK-WHO charts in the Red Book, also used by the HSE in Ireland, use the WHO standard from 2 weeks of age. In the first two weeks UK-WHO charts use British birth data, so the centile there can differ slightly. The UK-WHO chart draws lines at the 0.4th, 2nd, 9th, 25th, 50th, 75th, 91st, 98th and 99.6th centiles; the calculator on this page gives the exact centile.

Track every weigh-in

Growthling plots each weight on the WHO chart and shows its percentile, so you can see your baby’s curve from the first weeks. Free to sign up.

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Source: WHO Child Growth Standards, weight-for-age expanded tables. Related: How much weight should a baby gain per week? · What percentile should my baby be? For information only; not medical advice.