Definition
A centile (also called percentile) is a rank score showing the percentage of same-aged children who would score lower than the child being tested. A child at the 5th centile scores higher than 5% of peers and lower than 95%. The 50th centile is the median, the score the typical child achieves.
In context for parents
Key checkpoints
- A centile (percentile) is a rank score showing the percentage of same-aged children who would score lower.
- 50th centile is the median; 2nd centile (standardised score ~70) is a common "significant impairment" threshold.
- 5th centile (standardised score ~75) is the common DSM-5 / EACD threshold for DCD diagnosis.
- Centiles are not linear: distance between the 1st and 10th centiles in raw skill is larger than between the 50th and 60th.
- A child moving from the 2nd to the 9th centile after intervention has made significant gains, even though the absolute change looks modest.
Centiles are the most intuitive way to express assessment results to families and to schools. They map directly onto the standardised score bands (mean 100, SD 15):
- 98th centile and above: standardised score 130+ (top ~2%)
- 91st centile: standardised score 120
- 75th centile: standardised score 110
- 50th centile: standardised score 100 (the median)
- 25th centile: standardised score 90
- 16th centile: standardised score 85 (1 SD below mean)
- 9th centile: standardised score 80
- 5th centile: standardised score 75
- 2nd centile: standardised score 70 (2 SD below mean, clinically significant)
- 0.1st centile: standardised score 55 and below (extremely low)
For SEND diagnostic thresholds, the 5th centile (standardised score ~75) is a common cut-off, for example DCD diagnostic criteria require motor performance at or below the 5th centile. The 2nd centile (standardised score 70) is a frequent threshold for "significant impairment" in cognitive and language assessment.
Centiles are not linear. The distance between the 50th and 60th centiles in raw skill is small; the distance between the 1st and 10th is large. A child moving from the 2nd to the 9th centile after intervention has made significant gains, even though the absolute centile change looks modest.
For a child with a "spiky profile" on the WISC-V, centile reporting often makes the spike clearer than standardised scores. Verbal Comprehension at the 75th centile alongside Processing Speed at the 5th centile tells the story that Full Scale IQ at the 37th centile alone does not.
Related terms
The terms parents most often see alongside Centile.
Standardised Score
A score that compares a child's performance to a representative sample of the same age. The average is 100, with most children scoring between 85 and 115; scores below 70 or above 130 are unusual.
Wechsler Intelligence Scale for Children(WISC)
A widely used standardised assessment of cognitive ability for children aged 6-16, producing index scores for verbal comprehension, visual-spatial, fluid reasoning, working memory, and processing speed.
Where parents ask about this
Parents usually find this page after an EP, SaLT, or paediatric report has reported centile scores. Searches include "5th centile meaning", "centile versus standardised score", and "what does 2nd centile mean SEND". A Beaakon EP or SaLT can interpret centile scores in the context of your child's profile and explain what the numbers mean for school provision and EHCP wording.
References
The primary legislation, statutory guidance, research, and clinical tools this page draws on.