Work out weight percentile for children instantly with clear inputs, formula shown and shareable results.
The weight is turned into a z-score against the published mean and standard deviation for the child's age and sex, and the normal curve converts that into a centile. A single weight means little on its own; the centile places it against a reference population, and repeated centiles show whether growth is tracking.
Z-score
z = (weight - reference mean) / reference standard deviation
Centile
centile = normal cumulative distribution of z x 100
z = (weight - reference mean) / reference standard deviation. The weight is turned into a z-score against the published mean and standard deviation for the child's age and sex, and the normal curve converts that into a centile.
A single weight means little on its own; the centile places it against a reference population, and repeated centiles show whether growth is tracking.
Enter child's weight, reference mean weight for age, reference standard deviation. The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.