Baby Weight Percentile Calculator (WHO): Weight-for-Age Tables for 0–24 Months

“Your baby is in the 60th percentile for weight.” If you’ve heard that sentence from a pediatrician, you’ve probably also wondered: how did they get that number, and could I check it myself?

You can — in about thirty seconds. A WHO weight percentile compares your baby’s weight against the WHO Child Growth Standards: a reference population of healthy, breastfed children measured across six countries (Brazil, Ghana, India, Norway, Oman, and the USA) between 1997 and 2003. The standards cover 0–24 months with day-by-day precision, and the percentile tells you where your baby sits in that healthy range: heavier than X% of healthy same-age, same-sex babies.

Below are the complete WHO weight-for-age tables for boys and girls from birth to 24 months, at the 3rd, 10th, 25th, 50th, 75th, 90th, and 97th percentiles — the same underlying data Storklet’s in-app growth charts plot automatically.

How to use the tables

Three steps:

1. Find your baby’s age in the left column, in months (round to the nearest listed age).
2. Find your baby’s measured weight along that row, in kilograms. If your scale reads pounds, divide by 2.205.
3. Read the percentile at the top of the nearest column — that’s the number your pediatrician quotes.

Example: a 6-month-old girl who weighs 7.3 kg — find the 6-month row in the girls’ table, and 7.3 sits at the 50th percentile column: she’s exactly at the median. A 12-month-old boy at 11.8 kg — find 12 months in the boys’ table; 11.8 is at the 97th percentile: he’s at the top edge of the typical band.

Boys — WHO weight-for-age, 0–24 months (kg)

Age	P3	P10	P25	P50	P75	P90	P97
Birth	2.5	2.8	3.0	3.3	3.7	4.0	4.3
1 month	3.4	3.7	4.1	4.5	4.9	5.3	5.7
2 months	4.4	4.7	5.1	5.6	6.1	6.5	7.0
3 months	5.1	5.5	5.9	6.4	6.9	7.4	7.9
4 months	5.6	6.1	6.5	7.0	7.6	8.1	8.6
5 months	6.1	6.5	7.0	7.5	8.1	8.6	9.2
6 months	6.4	6.9	7.4	7.9	8.5	9.1	9.7
9 months	7.2	7.7	8.3	8.9	9.6	10.2	10.9
12 months	7.8	8.4	9.0	9.6	10.4	11.1	11.8
18 months	8.9	9.5	10.1	10.9	11.8	12.6	13.5
24 months	9.8	10.5	11.2	12.1	13.1	14.1	15.1

Girls — WHO weight-for-age, 0–24 months (kg)

Age	P3	P10	P25	P50	P75	P90	P97
Birth	2.4	2.7	2.9	3.2	3.6	3.9	4.2
1 month	3.2	3.5	3.8	4.2	4.6	5.0	5.4
2 months	4.0	4.3	4.7	5.1	5.6	6.1	6.5
3 months	4.6	5.0	5.4	5.8	6.4	6.9	7.4
4 months	5.1	5.5	5.9	6.4	7.0	7.5	8.1
5 months	5.5	5.9	6.3	6.9	7.5	8.1	8.7
6 months	5.8	6.3	6.7	7.3	7.9	8.5	9.2
9 months	6.6	7.0	7.6	8.2	8.9	9.6	10.4
12 months	7.1	7.7	8.2	8.9	9.7	10.5	11.3
18 months	8.2	8.8	9.4	10.2	11.1	12.0	13.0
24 months	9.2	9.8	10.6	11.5	12.5	13.5	14.6

These values are the weight-for-age percentiles from the WHO Child Growth Standards, published in 2006 after the Multicentre Growth Reference Study — the same reference your pediatrician’s chart paper uses, and the same dataset that powers Storklet’s growth charts.

Reading your result the way a pediatrician does

• The 50th percentile is the median, not a target. It’s the exact middle of the healthy reference population. Being above or below it is not better or worse.
• The 3rd to 97th band is the “typical” range — roughly 94% of healthy babies fall inside it. Being inside the band, at any point, is normal.
• Below the 3rd or above the 97th is a flag for closer attention, not a diagnosis. Plenty of healthy babies live outside the band.
• Percentile is not percentage. The 90th percentile is a rank — heavier than 90% of healthy peers — not “90% of some ideal weight.” And a single percentile point, from a single visit, is weak evidence on its own.

Four caveats before you read too much into it

1. Age precision matters. The full WHO data is day-by-day; these tables are rounded to month-level reference ages. A baby at 6 weeks is closer to the 1-month or 2-month rows depending on which side of the midpoint they fall. For a precise number, a charting tool that knows the exact day is better than a table.
2. Correct for prematurity. For babies born before 37 weeks, pediatricians typically use corrected age (age since the due date, not birth) when plotting growth, usually until age 2. Using uncorrected age on a preemie understates their percentile.
3. Sex-specific tables only. Boys and girls grow at different rates; the WHO publishes separate references, and the tables above must be read against the matching sex.
4. Scales and timing add noise. Weights taken on different scales, or at different times relative to feeds, vary by a few hundred grams — enough to move a percentile or two. Trends over months are far more reliable than any single reading.

Why WHO data — and why it matters for tracking

Not every calculator and chart you’ll find online uses the WHO standards. Many generic growth calculators pull from older or regional references, which gives different percentiles for the same baby. The WHO Child Growth Standards are the international benchmark — built from healthy, breastfed infants in favorable conditions — which is why WHO-based charts are the default in pediatric care worldwide.

That’s also why Storklet built its growth tracking on this exact data. Instead of hunting a table or re-entering measurements into a website, Storklet plots every logged weight directly onto the WHO weight-for-age curves and shows the percentile instantly — alongside the same for length and head circumference, on one timeline with feeding, sleep, and vaccine records. It works offline, keeps everything private on EU-hosted servers, shows no ads, and shares with unlimited caregivers on one plan. The growth and milestones tracker page walks through the full picture — or browse Storklet’s features to see the whole log.

The table above is a useful answer to “where does my baby sit?” — but the more valuable question is “where is my baby heading?” Consistent, logged measurements turn a single percentile into a growth story, and that story is what the WHO curves are designed to tell.

Sources and Further Reading

We base our explainers on high-quality academic research and public health standards.

WHO Child Growth Standards — weight-for-age tables (0–24 months)

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WHO Multicentre Growth Reference Study — study design and implementation

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WHO: Training course on child growth assessment (how to use the charts)

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