What does centile mean?
A centile is one of the hundred equal divisions into which an ordered set of data can be split, used chiefly to state where an individual measurement stands relative to a reference population. To say that a child's height is on the 75th centile means that, compared with children of the same age and sex, roughly three-quarters are shorter and one-quarter taller. The term is a staple of medical statistics — particularly paediatric growth charts — as well as educational testing and psychological measurement, and it appears more often in British English than in American English, where 'percentile' is preferred. Because a centile describes rank rather than proportion, it should not be confused with a percentage: a score in the 90th centile is not a score of 90 per cent but one bettered by only a tenth of the group. Its precision and neutrality make it invaluable wherever distributions, not raw scores, carry the meaning.
nounOne of the values in a statistical distribution that divides it into a hundred equal groups; a single point on the scale of percentiles. A measurement is said to be 'in' or 'on' a given centile when it falls at that position relative to a reference population.
- A value marking one of the hundred equal divisions of an ordered statistical distribution, especially used to report where an individual measurement ranks against a reference population (as in child growth charts).
"The baby's weight was on the 60th centile for her age, well within the healthy range."
"Head circumference tracking along the same centile over time is generally reassuring to paediatricians."
"Pupils scoring below the fifth centile on the assessment were flagged for additional support."
The plural refers either to multiple centile values on a scale or to the divisions themselves, as in 'growth centiles' or 'the outermost centiles of the distribution'.
"The chart plots weight-for-age across all the centiles from the 3rd to the 97th."
If your baby is on the 90th centile for height, it doesn't mean they're 90% as tall as other babies — it means they're taller than roughly 90 of every 100 babies their age.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of centile
Centile derives from the Latin root 'centum', meaning 'hundred', combined with the suffix '-ile' used to form adjectives and related nouns. It was formed on the model of earlier statistical terms such as 'percentile' and 'quartile', which likewise divide a distribution into equal parts. Its cognates from the same Latin root include 'percent', 'century', and 'centime'.
How centile is actually used
The word belongs chiefly to formal, technical registers — medicine (especially paediatrics), education, and psychometrics — and is far more common in British English than American English, where 'percentile' dominates. It is conventionally used with ordinal numerals ('the 75th centile') rather than cardinals, and one says a measurement is 'on' or 'at' a centile, not 'in a centile group'.
Easily confused with centile
'Percentile' is the more general term for the whole scale of hundredths, while 'centile' typically refers to one specific division or position on that scale; the two are closely related and often used interchangeably.
A percentage expresses a proportion out of a hundred of any quantity, whereas a centile expresses rank within a distribution — being in the 90th centile does not mean scoring 90%.