Growth calculator: check weight and height against the WHO charts

Check the growth

Age in months, sex, then weight or height — no need for both; whichever you have on hand.

What to enter and what the number means

The tool runs on the World Health Organization growth charts — the same ones printed in your doctor's file and on the back of the immunisation card. The answer is a percentile.

The 50th percentile is the midpoint: out of a hundred children, about fifty measure less than yours and fifty more. The 15th percentile means fifteen measure less, eighty-five more.

WHO's charts were built from healthy, well-nourished, predominantly breastfed children around the world — India included. They show what healthy growth looks like, not what the average child in any one place weighs.

What a percentile is — and isn't

Percentiles are not marks. The 90th is not 'better' than the 15th. Both are on the chart, and both can be perfectly healthy.

The large majority of healthy children track somewhere between the 3rd and 97th lines. A child moving steadily along the 15th line is most likely simply built that way — small parents tend to have children on the lower lines, as expected.

And two children's percentiles are not for comparing. A growth chart is one child measured against their own past — not a race against the neighbour's baby.

Not a dot — the shape of the line

The most important sentence on this page: a single measurement tells you almost nothing. A growth chart is a line over time, and the meaning is in the line's shape.

A baby steady on the 15th line for six months is fine. A baby sliding from the 90th to the 50th to the 25th — even while still 'in the normal range' — is worth checking.

So this tool answers with one number, but the real verdict lives in your doctor's file, where all the past visits' dots are joined. Use this alongside that file, not instead of it.

The errors that sneak into measurements

A home weighing with clothes and a nappy reads three hundred to five hundred grams heavy. Clinics weigh babies undressed — which is why home and clinic numbers never match.

Children under two are measured lying down, not standing — and a lying measurement reads about half to one centimetre longer than a standing one. Measuring the same way every time matters more than the number itself.

And count age in months, precisely. At young ages a single month's error moves the percentile a long way — a three-month-old's weight on the four-month row will worry you for nothing.

Head circumference — the third measurement

At every visit the doctor measures three things: weight, height, head circumference. The third gets the least attention and says the most in the first two years, because head growth is brain growth, directly.

At birth the head measures about thirty-five centimetres and grows twelve more in the first year — half of that in the first three or four months. It isn't in this tool because it's hard to measure correctly at home; the tape must cross above the eyebrows and around the widest point at the back.

But it's in your file, and worth looking at there. A circumference suddenly crossing lines upward, or stalling, are both same-week conversations with the doctor.

What actually helps — and when to see the doctor

Exclusive breastfeeding to six months, then home-cooked solids introduced and built up — growth needs little more than that. Preventing repeated diarrhoea and chest infections is the other half.

Skip the 'weight gain' powders and appetite syrups unless a doctor prescribes them. Some children are simply lean, and need nothing.

See the doctor if: weight crosses two lines downward on the chart, weight gain stalls, birth weight isn't regained by two weeks, or a flat line comes with a listless baby. Catching these early is what the regular weigh-ins — including the monthly anganwadi one — are for.

Questions

Q: My baby is on the 10th percentile — should I worry? — Not from one measurement. Steady on the same line, happy and active — that's most likely just the build. It's a fall across lines that warrants a check.

Q: Why separate charts for boys and girls? — Because their average growth differs. On a single chart, girls would read falsely light.

Q: What about premature babies? — They're tracked on 'corrected age' — subtract the weeks of prematurity — usually until about age two. Your doctor will tell you the corrected age to use.

Q: Weight dipped during illness or teething — bad? — A few days' dip is normal, and babies catch it back up after. Only weeks of no gain in a row are worth a visit.