Baby Weight Chart by Month in KG (0 to 12 Months): WHO Average Weight for Boys and Girls (2026 Guide)

TL;DR

On average, a baby weighs about 3.2 to 3.3 kg at birth, doubles their birth weight by around 4 to 5 months, and triples it by about 1 year (roughly 9 to 9.6 kg). Boys are usually slightly heavier than girls (WHO) (CDC)。 But the single most important thing is not the exact number, it is the trend: a healthy baby grows steadily along their own curve on the growth chart. Some healthy babies sit on a lower percentile and some on a higher one, both are fine if growth is steady. Breastfed and formula-fed babies can grow at slightly different rates. Use the chart below as a general guide, and let your paediatrician track your baby's growth at regular checkups. Worry about the pattern (flat or falling growth), not one reading.

Quick Answer

On average, a baby weighs about 3.2 to 3.3 kg at birth, doubles it by around 4 to 5 months, and triples it by about 1 year (roughly 9 to 9.6 kg). Boys are usually slightly heavier than girls. The most important thing is the trend, not the exact number: a healthy baby grows steadily along their own curve. Some healthy babies are on lower percentiles and some higher. Let your paediatrician track growth at regular checkups.

Author: Mittali Khurana, Senior Child Health Content Editor, Mylo Parenting Desk Medically reviewed against: WHO Child Growth Standards, IAP Growth Charts and AAP / HealthyChildren guidance Last updated: 29 June 2026

Medical Disclaimer: This article is for informational purposes only and is not a substitute for professional medical advice. The chart shows average values, individual healthy babies vary. Your paediatrician tracks your baby's growth on a proper growth chart. If your baby's weight is not gaining, is falling across percentiles, or you are worried, see your paediatrician.

Key Takeaways

• Average birth weight is about 3.2 to 3.3 kg (WHO) (WHO)
• Babies usually double birth weight by 4 to 5 months
• Babies usually triple birth weight by about 1 year
• Boys are usually slightly heavier than girls
• The trend matters more than the exact number
• A baby on a lower or higher percentile can be perfectly healthy if growing steadily
• Breastfed and formula-fed babies may grow at slightly different rates
• Worry about flat or falling growth, not a single reading

Baby Weight Chart by Month (KG): 0 to 12 Months

These are WHO 50th percentile (average) weights, the most widely used international standard (WHO):

How to read this: The 50th percentile is the average, half of healthy babies weigh more, half weigh less. Your baby being above or below this is not automatically a problem. What matters is steady growth along their own curve (CDC)。

Baby Height (Length) Chart by Month: 0 to 12 Months

Approximate healthy length range (WHO-based) (WHO):

How Much Weight Should a Baby Gain Each Month?

Babies grow fastest in the early months, then slow down (AAP/HealthyChildren):

Newborns often lose a little weight (up to about 7 to 10%) in the first few days, then regain their birth weight by about 2 weeks, this is normal (NHS)。

Key Weight Milestones (Doubling and Tripling)

A simple way to track healthy growth (AAP/HealthyChildren):

Note: A common myth is that babies "double their weight by 7 months." In fact, most babies double by 4 to 5 months and triple by their first birthday (CDC)。

What Affects a Baby's Weight?

Many normal factors influence weight, so do not compare your baby to others (WHO) (NHS):

Breastfed vs Formula-Fed: Do They Grow Differently?

Yes, slightly, and both are normal (WHO):

• Breastfed babies often gain a bit faster in the first 2 to 3 months, then a little slower later
• Formula-fed babies may gain slightly more after a few months
• The WHO charts are based on breastfed babies as the norm
• Both feeding methods support healthy growth, follow your paediatrician

When Should You Worry About Your Baby's Weight?

See your paediatrician if (NHS) (AAP/HealthyChildren):

• Your baby's weight is not increasing over time
• Your baby is falling across percentile lines on the growth chart
• Your baby is not regaining birth weight by 2 to 3 weeks
• There are fewer wet/dirty nappies than expected (a feeding sign)
• Your baby seems very lethargic, not feeding well, or unwell

A single low reading is usually fine. The concern is a downward trend or a baby who is not gaining, which your paediatrician will assess.

Indian Context: What Indian Parents Should Know

1. Use WHO or IAP charts: Indian paediatricians use WHO standards and IAP growth charts; your baby's clinic chart is the real reference (IAP)
2. Do not over-compare: Avoid comparing your baby to relatives' babies; every baby has their own curve
3. Don't overfeed for "chubby = healthy": A bigger baby is not always healthier; steady growth matters more
4. Exclusive breastfeeding to 6 months: Recommended, with solids added from 6 months (WHO)
5. Immunisation visits: Use routine vaccination visits to get your baby weighed and growth tracked
6. Low birth weight is common in India: Premature or LBW babies need extra paediatric follow-up, do not panic, follow medical advice

Myths vs Facts About Baby Weight

FAQs: Baby Weight Chart 0 to 12 Months

What is the average baby weight by month?

On the WHO average, boys go from about 3.3 kg at birth to 9.6 kg at 12 months, and girls from about 3.2 kg to 8.9 kg (WHO)。 See the chart above. These are averages, healthy babies vary, and the trend matters most.

Bachche ka weight har mahine kitna hona chahiye? (Hinglish)

Average ke hisaab se, ladke janm ke samay lagbhag 3.3 kg se 12 mahine mein 9.6 kg, aur ladkiyan 3.2 kg se 8.9 kg tak hoti hain. Lekin yeh sirf average hai, har baby alag hota hai. Sabse zaruri hai ki baby apne curve par steadily badh raha ho. Number se zyada growth ka trend maayne rakhta hai. Apne paediatrician se growth track karwayein.

How much weight should a 3-month-old baby weigh?

On average, about 6.4 kg for boys and 5.8 kg for girls at 3 months (WHO)。 Being a little above or below is normal. What matters is that your baby is growing steadily along their own curve.

When does a baby double and triple their birth weight?

Most babies double their birth weight by about 4 to 5 months and triple it by about 12 months (AAP/HealthyChildren)。 The "double by 7 months" idea is a myth, doubling usually happens earlier.

Mera baby chart se halka hai, chinta ki baat hai? (Hinglish)

Zaroori nahi. Kuch healthy babies lower percentile par hote hain aur kuch higher par, dono normal ho sakte hain agar baby steadily badh raha hai. Chinta tab hai jab weight badhna ruk jaye ya percentile lines neeche gir jayein. Ek single reading se ghabrayein nahi. Doctor se growth chart par track karwayein.

Do breastfed and formula-fed babies weigh differently?

Slightly, and both are normal (WHO)。 Breastfed babies often gain a bit faster early on and slower later; formula-fed babies may gain slightly more after a few months. The WHO charts are based on breastfed babies. Both support healthy growth.

When should I worry about my baby's weight?

See your paediatrician if your baby's weight is not increasing, is falling across percentile lines, is not regaining birth weight by 2 to 3 weeks, or your baby is feeding poorly or seems unwell (NHS)。 A single low reading is usually fine; a downward trend needs review.

Which growth chart is used in India?

Indian paediatricians use the WHO Child Growth Standards and the IAP (Indian Academy of Pediatrics) growth charts (IAP)。 Your baby's clinic growth chart is the real reference, plotted at each visit.

References

1. WHO. "Weight-for-Age (Child Growth Standards)." https://www.who.int/tools/child-growth-standards/standards/weight-for-age
2. WHO. "Length/Height-for-Age." https://www.who.int/tools/child-growth-standards/standards/length-height-for-age
3. CDC. "WHO Growth Charts." https://www.cdc.gov/growthcharts/who_charts.htm
4. AAP / HealthyChildren. "Baby Growth and Development." https://www.healthychildren.org/English/ages-stages/baby/Pages/default.aspx
5. NHS UK. "Baby Weight and Height." https://www.nhs.uk/conditions/baby/babys-development/height-weight-and-reviews/baby-weight-and-height/
6. Indian Academy of Pediatrics (IAP). "IAP Growth Charts." https://iapindia.org/

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