Quick answer: A healthy baby roughly doubles their birth weight by 5 months and triples it by 12 months. Weight gain is fastest in the first 3 months (about 150–200g a week) and slows steadily after that — this slowing down is normal, not a problem. Any weight between the 3rd and 97th percentile on the WHO chart below is medically normal. What matters most is that your baby keeps growing along their own line, not which number they sit on.
The WHO Weight-for-Age Chart (Birth to 12 Months)
These are the official WHO 2006 Child Growth Standards — the chart the Indian Academy of Pediatrics (IAP) recommends for all Indian children under 5. Boys and girls have separate charts because boys are, on average, slightly heavier.
- 3rd percentile = the lower edge of normal
- 50th percentile = the median (exactly average — not a target to hit)
- 97th percentile = the upper edge of normal
Anywhere between the 3rd and 97th line is healthy.
Boys — weight in kg
| Age | 3rd percentile | 50th (median) | 97th percentile |
|---|---|---|---|
| Birth | 2.5 | 3.3 | 4.3 |
| 1 month | 3.4 | 4.5 | 5.7 |
| 2 months | 4.4 | 5.6 | 7.0 |
| 3 months | 5.1 | 6.4 | 7.9 |
| 4 months | 5.6 | 7.0 | 8.6 |
| 5 months | 6.1 | 7.5 | 9.2 |
| 6 months | 6.4 | 7.9 | 9.7 |
| 7 months | 6.7 | 8.3 | 10.2 |
| 8 months | 7.0 | 8.6 | 10.5 |
| 9 months | 7.2 | 8.9 | 10.9 |
| 10 months | 7.5 | 9.2 | 11.2 |
| 11 months | 7.7 | 9.4 | 11.5 |
| 12 months | 7.8 | 9.6 | 11.8 |
Girls — weight in kg
| Age | 3rd percentile | 50th (median) | 97th percentile |
|---|---|---|---|
| Birth | 2.4 | 3.2 | 4.2 |
| 1 month | 3.2 | 4.2 | 5.4 |
| 2 months | 4.0 | 5.1 | 6.5 |
| 3 months | 4.6 | 5.8 | 7.4 |
| 4 months | 5.1 | 6.4 | 8.1 |
| 5 months | 5.5 | 6.9 | 8.7 |
| 6 months | 5.8 | 7.3 | 9.2 |
| 7 months | 6.1 | 7.6 | 9.6 |
| 8 months | 6.3 | 7.9 | 10.0 |
| 9 months | 6.6 | 8.2 | 10.4 |
| 10 months | 6.8 | 8.5 | 10.7 |
| 11 months | 7.0 | 8.7 | 11.0 |
| 12 months | 7.1 | 8.9 | 11.3 |
Source: WHO Child Growth Standards (weight-for-age, 2006). Values rounded to one decimal place.
Read it as a range, not a target. If your baby sits steadily on the 15th or 25th percentile, that is a perfectly healthy baby who is simply built lean. A baby does not need to reach the 50th percentile.
The Normal Weight Gain Trend, Month by Month
Weight gain is not steady across the first year — it starts fast and slows down. This is the single most misunderstood thing about baby weight. A baby who gained 1 kg in month one but only 300g in month nine is growing exactly as expected.
First 2 weeks — a dip, then recovery
Newborns lose up to 7–10% of their birth weight in the first few days. This is normal. They stop losing by day 4–5 and are usually back to birth weight by 10–14 days.
See your pediatrician if your baby loses more than 10% of birth weight, or hasn’t returned to birth weight by 2 weeks.
0–3 months — the fastest phase
About 150–200g per week (roughly 25–30g a day). Babies roughly double their birth weight by 4–5 months.
3–6 months — still rapid, slightly slower
About 100–150g per week.
6–9 months — slowing down
About 70–90g per week. Once babies become mobile (rolling, crawling) and start solids, the rate naturally eases.
9–12 months — the slowest phase of the year
About 50–75g per week. Babies triple their birth weight by around 12 months.
| Age band | Average weight gain |
|---|---|
| 0–3 months | 150–200g / week |
| 3–6 months | 100–150g / week |
| 6–9 months | 70–90g / week |
| 9–12 months | 50–75g / week |
These are averages. Breastfed and formula-fed babies can follow slightly different curves, and a baby born small (under 2.5 kg) may grow faster than this as they catch up. Your pediatrician looks at the trend on the chart, not any single number.
What Actually Matters: The Trend, Not One Number
A single weigh-in tells you very little. Two or three weights plotted over time tell the whole story.
- A baby following their own curve is healthy — whether that curve is the 10th, 50th, or 90th percentile.
- A baby crossing downward through percentile lines (say, 50th → 25th → 10th over a few visits) is what gets a pediatrician’s attention — not a baby who has always been on the 10th.
You can plot your baby’s weight at home with Babynama’s Growth Chart Tool — you’ll need their weight (on a proper infant scale, undressed), exact age, and sex.
For what percentiles actually mean and the WHO-vs-Indian-chart confusion, read: Is My Baby’s Weight Normal? Growth Charts & Percentiles Explained.
When to Actually Worry
Contact your pediatrician if you notice:
- Crossing two or more percentile lines downward over 2–3 visits
- Any weight loss after the newborn period (after 2 weeks), outside of a short illness
- No weight gain for over a month in a baby under 6 months
- Weight below the 3rd percentile and still falling
- Birth-weight loss over 10%, or not back to birth weight by 14 days
- Poor feeding together with poor weight gain — the combination matters more than either alone
- Fewer wet nappies, unusual sleepiness, or low energy alongside slow gain
A baby who is feeding well, has plenty of wet nappies, is active and alert, and is meeting milestones is almost always growing fine — even on a low percentile.
A Quick Word on the “Chubby Baby” Pressure
In many Indian families, a fat baby is seen as a healthy baby. But a lean, normally-growing baby on the 15th–25th percentile is not underweight, and switching a breastfed baby to formula or starting solids early “to fatten them up” usually doesn’t change a genetically lean baby’s curve — it can do more harm than good. The goal is a consistently growing baby, not a heavier one.
Frequently Asked Questions
How much weight should my baby gain in a month?
Roughly 600–900g a month in the first 3 months, slowing to about 300–450g a month by the second half of the first year. Weight gain naturally slows as your baby gets older — that’s expected.
My baby is on the 10th percentile. Is that bad?
No. The 10th percentile is well within normal. A baby who has been on the 10th since birth, feeds well, and is developing normally is a healthy baby. Percentiles are a ranking, not a grade.
When does a baby double and triple their birth weight?
Most babies double their birth weight by about 5 months and triple it by about 12 months.
Which chart should I use — WHO or an Indian chart?
The WHO 2006 chart (the one above). The IAP has recommended it for all Indian children under 5 since 2015. Older Indian charts were based on undernourished populations and can make poor growth look acceptable.
Why has my baby’s weight gain slowed down?
Because that’s the normal trend. The fastest gain is in the first 3 months and it slows every month after. As long as your baby keeps moving along their own curve, slower gain later in the year is exactly what should happen.
This article is general information for parents in India and follows IAP and WHO 2006 growth guidance. It is not a substitute for an in-person assessment by your pediatrician, who knows your baby’s full history. For any urgent concern, contact your pediatrician or the nearest hospital, or call 112 (national emergency) or 108 (ambulance).
Worried about your baby’s weight? Book a consultation with a Babynama pediatrician, or explore our Care Plans for 24/7 expert support.
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