Baby Weight and Height Charts by Month: WHO Standards

Every parent wants to know: is my baby growing normally? The World Health Organization (WHO) has spent decades collecting growth data from healthy children worldwide. The result: the most reliable reference charts available — and what every pediatrician uses.

Here's what you need to know about interpreting these charts, with the actual numbers.

What Are WHO Growth Charts?

WHO growth charts track six measurements: weight-for-age, height-for-age, weight-for-height, head circumference, arm circumference, and BMI. For most parents, the first three are most relevant.

Charts are split by sex — boys and girls grow at different rates, especially in the first two years.

Results are expressed as percentiles. A baby at the 50th percentile is exactly average. The 25th percentile means they're larger than 25% of babies their age. Neither high nor low percentiles are automatically good or bad — the trend matters more than a single measurement.

Weight-for-Age: Boys (50th Percentile)

Age	Weight (kg)	Weight (lb)
Birth	3.3	7.3
1 month	4.5	9.9
2 months	5.6	12.3
3 months	6.4	14.1
4 months	7.0	15.4
6 months	7.9	17.4
9 months	9.2	20.3
12 months	10.2	22.5
18 months	11.5	25.4
24 months	12.5	27.6

Weight-for-Age: Girls (50th Percentile)

Age	Weight (kg)	Weight (lb)
Birth	3.2	7.1
1 month	4.2	9.3
2 months	5.1	11.2
3 months	5.8	12.8
4 months	6.4	14.1
6 months	7.3	16.1
9 months	8.6	19.0
12 months	9.5	20.9
18 months	10.8	23.8
24 months	12.0	26.5

Height-for-Age: Boys (50th Percentile)

Age	Height (cm)	Height (in)
Birth	49.9	19.6
1 month	54.7	21.5
2 months	58.4	23.0
3 months	61.4	24.2
4 months	63.9	25.2
6 months	67.6	26.6
9 months	72.3	28.5
12 months	75.7	29.8
18 months	82.3	32.4
24 months	87.8	34.6

Height-for-Age: Girls (50th Percentile)

Age	Height (cm)	Height (in)
Birth	49.1	19.3
1 month	53.7	21.1
2 months	57.1	22.5
3 months	59.8	23.5
4 months	62.1	24.4
6 months	65.7	25.9
9 months	70.1	27.6
12 months	73.9	29.1
18 months	80.7	31.8
24 months	86.4	34.0

How to Read the Chart Correctly

Single measurements mean little

A snapshot tells you where your baby is today. What matters is whether they're following their own curve. A baby consistently at the 10th percentile is perfectly healthy — they're just small. Concern arises when a baby drops two or more percentile bands between visits.

Weight gain by phase

Babies grow fastest in the first months:

• 0–3 months: ~200 g/week (about 30 g/day)
• 3–6 months: ~130 g/week
• 6–12 months: ~70–90 g/week
• After 12 months: ~50 g/week

If weight gain slows dramatically, talk to your pediatrician.

Head circumference matters too

Head circumference reflects brain growth. Normal range at birth: 33–37 cm. It grows about 2 cm per month in the first three months, then slows. Your pediatrician measures this at every visit.

Premature Babies: Corrected Age

For babies born before 37 weeks, always use corrected age (chronological age minus weeks premature) when interpreting growth charts — until age 2 for moderate prematurity, age 3 for extreme prematurity.

A baby born 8 weeks early who is 4 months old should be plotted at 2 months on the growth chart.

When to See Your Pediatrician

Schedule a visit (don't wait for the next routine check) if:

• Your baby drops 2+ percentile bands between measurements
• Weight gain stops for 2+ weeks under 6 months, or 4+ weeks after 6 months
• Head circumference is below P3 or above P97
• You're worried — trust your gut

How to Track Accurately

Weigh babies naked, on the same scale. Measure length lying down (under 2 years) — standing measurements are up to 2 cm shorter. Take measurements at the same time of day.

A single pediatric visit gives you one data point. Tracking at home between visits gives you the trend — which is what matters.

The best approach: record every measurement with dates in a baby growth tracker, so you can see the curve building over time. When your pediatrician asks "how has weight gain been?", you'll have a real answer — not a guess.