Baby Weight Gain Chart by Month (WHO), 0–2 Years

Growth · 6 min read · Updated 28 September 2026

Key points

The WHO chart shows a healthy range, not one ideal weight — most healthy babies sit somewhere inside it.
Steady growth along the baby's own curve matters more than any single reading.
Babies often lose some weight in the first days and are usually back to birth weight by about 2 weeks.
On the WHO median, babies roughly double their birth weight by about 4 months.
Premature babies are plotted by corrected age, not their age from birth.

See a doctor now if you notice

Not back to birth weight by 2 weeks of age
Weight dropping across chart lines, or no gain between two visits
Fewer than 6 wet nappies a day after the first week
Poor feeding, very sleepy or hard to wake for feeds
Repeated vomiting, or vomit that is green

How much should my baby weigh?

The table below comes from the WHO Child Growth Standards, which describe how healthy breastfed babies grow in good conditions. The middle value is the median — half of healthy babies weigh more and half weigh less. The range covers the large majority of healthy babies (from −2 to +2 standard deviations).

A baby near either end of the range can be perfectly healthy. What the doctor watches is the pattern: a baby who keeps following their own curve is usually growing well.

WHO weight-for-age, birth to 2 years (kg)
Age	Boys — median	Boys — healthy range	Girls — median	Girls — healthy range
Birth	3.3	2.5 – 4.4	3.2	2.4 – 4.2
1 month	4.5	3.4 – 5.8	4.2	3.2 – 5.5
2 months	5.6	4.3 – 7.1	5.1	3.9 – 6.6
3 months	6.4	5.0 – 8.0	5.8	4.5 – 7.5
4 months	7.0	5.6 – 8.7	6.4	5.0 – 8.2
5 months	7.5	6.0 – 9.3	6.9	5.4 – 8.8
6 months	7.9	6.4 – 9.8	7.3	5.7 – 9.3
9 months	8.9	7.1 – 11.0	8.2	6.5 – 10.5
12 months	9.6	7.7 – 12.0	8.9	7.0 – 11.5
18 months	10.9	8.8 – 13.7	10.2	8.1 – 13.2
24 months	12.2	9.7 – 15.3	11.5	9.0 – 14.8

Source: WHO weight-for-age z-score tables (median and −2 SD to +2 SD), rounded to 0.1 kg.

Weight in the first two weeks

It is normal for a newborn to lose some weight in the first few days while feeding gets established. Most babies are back to their birth weight by about 2 weeks.

If your baby is losing a lot of weight, is not back to birth weight by 2 weeks, or is not feeding well, see the doctor — early help with feeding makes a big difference.

How to read your baby's growth chart

At each visit the doctor plots weight, length and head size on the chart. One reading tells us little; a line of readings shows whether your baby is growing steadily.

Following a curve, even a low or high one, is usually reassuring
Crossing two or more main lines downwards needs a review
Weigh on the same scale, with the baby in minimal clothing, when you can
Bring your baby's health card to every visit so readings can be compared

Premature babies: use corrected age

A baby born early is plotted using corrected age — their age from birth minus the number of weeks they were born early. A baby born 8 weeks early is compared with 2-month-olds when they are 4 months old. Doctors usually use corrected age for growth until about 2 years.

Questions parents ask

What is a normal weight for a 6-month-old baby?

On the WHO chart, the median weight at 6 months is 7.9 kg for boys and 7.3 kg for girls. Healthy babies range from about 6.4 to 9.8 kg (boys) and 5.7 to 9.3 kg (girls). Steady growth along your baby's own curve matters more than the exact number.

My baby is below the median. Is that a problem?

Not by itself. Half of all healthy babies are below the median. The doctor looks at whether your baby is growing steadily, feeding well and meeting milestones.

How often should my baby be weighed?

Your baby is usually weighed at each vaccination and check-up visit. Weighing too often at home can be confusing, because normal day-to-day changes look bigger than they are.

Can I use the WHO chart for a premature baby?

Yes, once your baby reaches their due date — using corrected age. Before that, the doctor uses a growth chart made for premature babies.

This guide is general health information for parents. It is not a diagnosis and does not replace a visit to your child's doctor. If you are worried, call us — we are open 24 hours for emergencies.

Sources