Baby Weight Chart By Month In KG (Boys & Girls)

If you are looking for a baby weight chart by month in kg, this guide gives you the healthy weight range for each month from birth to 2 years, for boys and girls, based on the World Health Organization (WHO) Child Growth Standards. These are the growth charts recommended for all children under 5, including in Pakistan.

The most important thing to know first: a baby weight chart shows a range, not a single "correct" weight. Any weight between the 3rd and 97th line is considered healthy. Where your baby sits matters far less than whether they keep growing steadily along their own curve over time. A baby who is consistently on the 15th percentile is just as healthy as one on the 85th.

Below you will find separate weight charts for boys and girls in kilograms, plus simple guidance on how to read them and when to speak to a doctor. This is a general reference — your paediatrician, who tracks your baby's trend at each visit, is always the best guide.

Quick Answer

In short:

At birth, the WHO median weight is about 3.3 kg for boys and 3.2 kg for girls.

By 6 months, the median is about 7.9 kg for boys and 7.3 kg for girls.

By 1 year, the median is about 9.6 kg for boys and 8.9 kg for girls.

The full healthy range at any age runs from the 3rd to the 97th percentile — the chart below gives both.

Steady growth along your baby's own curve matters more than the exact number.

Baby Boy Weight Chart by Month (kg)

This chart shows WHO weight-for-age values for boys in kilograms. The median (50th percentile) is the middle, average weight. The 3rd and 97th percentiles mark the edges of the normal range — most healthy babies fall between them.

Source: WHO Child Growth Standards, weight-for-age (boys), values in kg. Figures for 13–23 months are shown at 3-month steps (15, 18, 21 months) to keep the chart readable.

Baby Girl Weight Chart by Month (kg)

This chart shows WHO weight-for-age values for girls in kilograms. Girls typically track a little lighter than boys of the same age — about 300 to 500 g on average across the first year — which is why the charts are separate.

Source: WHO Child Growth Standards, weight-for-age (girls), values in kg. Figures for 13–23 months are shown at 3-month steps (15, 18, 21 months) to keep the chart readable.

How to Read a Baby Weight Chart

A weight chart uses percentiles. If your baby is on the 50th percentile, they weigh more than half of babies their age and less than the other half — right in the middle. The 3rd percentile means about 3 in 100 babies weigh less; the 97th means about 3 in 100 weigh more. Anywhere between the 3rd and 97th is a normal, healthy weight.

A percentile is a rank, not a grade. The 25th percentile does not mean your baby is "behind" — it means they are simply built a little leaner than average, which is perfectly healthy. Babies come in different sizes, just as adults do.

The single most important idea:

Doctors look at the trend, not one number. A baby who has always followed the 15th percentile is growing well. What draws attention is a baby crossing downward through several lines over a few visits — for example 50th to 25th to 10th. One weigh-in tells you little; the pattern over time tells the story.

Normal Weight-Gain Milestones

Alongside the chart, these general patterns from paediatric guidance can reassure you:

•     Newborns often lose 5 to 10 percent of their birth weight in the first few days, and usually regain it by about 2 weeks of age.

•     Most babies double their birth weight by around 4 to 5 months.

•     Most babies triple their birth weight by around 12 months.

•     Weight gain is fastest in the early months and naturally slows through the first year and into toddlerhood.

These are averages. A baby born small — for example under 2.5 kg — may gain faster as they catch up, and premature babies are tracked using their corrected age. Your paediatrician will interpret the chart for your baby's situation.

What Affects a Baby's Weight

Many normal factors influence where a healthy baby sits on the chart, including:

•     Genetics — taller or bigger parents often have bigger babies, and vice versa.

•     Birth weight and whether the baby was born early or on time.

•     Feeding — breastfed and formula-fed babies can follow slightly different curves, both healthy.

•     Sex — boys are on average slightly heavier than girls, which is why charts are separate.

•     Illness — a temporary illness can slow weight gain for a short time, usually recovering afterward.

Because of all this variety, a single number is far less meaningful than your baby's own steady pattern of growth.

When to Speak to a Doctor

A weight chart is a guide, not a diagnosis. Speak to your paediatrician or Lady Health Worker if you notice any of the following, rather than acting on the numbers alone:

•     Your baby's weight is crossing downward through percentile lines over several visits.

•     Your baby is not regaining birth weight by about 2 to 3 weeks of age.

•     Your baby seems to be gaining very little, or losing weight, over time.

•     Your baby has far fewer wet nappies than usual, is very sleepy or hard to wake, or is feeding poorly.

•     You are simply worried about your baby's growth or feeding — it is always reasonable to ask.

Weighing your baby undressed on a proper infant scale, at the same kind of time of day, gives the most reliable readings. Routine well-baby visits are the best way to keep track.

Frequently Asked Questions

What is the average baby weight by month in kg?

Using WHO medians: at birth about 3.3 kg (boys) and 3.2 kg (girls); at 6 months about 7.9 kg (boys) and 7.3 kg (girls); at 1 year about 9.6 kg (boys) and 8.9 kg (girls). These are averages — the full healthy range runs from the 3rd to the 97th percentile shown in the charts above.

My baby is on the 10th percentile. Is that bad?

No. The 10th percentile is within the normal range. A baby who consistently tracks around the 10th percentile and is feeding well and active is growing exactly as expected. What matters is steady growth along their own curve, not the number itself.

Which chart should I use — WHO or CDC?

For children under 5, the WHO Child Growth Standards are recommended internationally, including in Pakistan, because they describe how healthy children grow under optimal conditions. This article uses WHO data. Your clinic may plot on the same WHO chart at each visit.

Do breastfed and formula-fed babies weigh differently?

They can follow slightly different curves — both are healthy. The WHO charts are based on healthy, predominantly breastfed babies. Your paediatrician interprets your baby's own pattern regardless of feeding method.

How often should my baby be weighed?

At routine well-baby checks is usually enough for healthy babies. Weighing too often at home can cause needless worry, because small day-to-day differences are normal. If your doctor wants closer monitoring, they will advise a schedule.

My baby was born premature. How do I read the chart?

Premature babies are usually tracked using their corrected age (age from the due date, not the birth date) for the first couple of years. Ask your paediatrician, who will plot and interpret the chart correctly for your baby.

When do babies double and triple their birth weight?

Most babies double their birth weight by around 4 to 5 months and triple it by around 12 months. These are averages; some healthy babies reach them a little earlier or later.

Conclusion

A baby weight chart by month in kg is a helpful reference, but it is best read as a range rather than a target. The WHO charts above show the healthy band — from the 3rd to the 97th percentile — for boys and girls from birth to 2 years. A baby anywhere in that range, growing steadily along their own curve, is a healthy baby.

Try not to worry about a single number or about reaching the 50th percentile. Focus on steady growth over time, regular feeding, and plenty of wet nappies. Keep up routine well-baby visits, and if you ever have concerns about your baby's weight or feeding, your paediatrician or Lady Health Worker is the best person to help.

Medical Disclaimer

This article is for general information and education only. It is not a substitute for professional medical advice, diagnosis or treatment. Growth patterns differ from child to child, and babies born prematurely or with medical conditions may need different interpretation. Always consult a qualified paediatrician or registered health professional about your own child's growth, weight or health. If you are worried about your baby's weight or feeding, seek medical advice.