UK Boys Height Percentile

UK-WHO chart percentiles for boys aged 2 weeks to 4 years — the charts used across the UK. Enter age (months + days) and height or length for an exact percentile and z-score.

Please note: these are educational estimates based on published growth references, not medical advice. If you have concerns about a child's growth, consult a pediatrician.

UK-WHO percentile

Ages 14 days – 48 months. Under 24 months measure length lying down; from 24 months measure standing height.

Age

days

Height

Honest coverage note: the RCPCH UK-WHO charts officially use WHO data from 2 weeks to 4 years, so these percentiles are computed from the WHO tables. From age 4 the UK charts use the British 1990 reference, whose tables aren't openly licensed — we don't bundle them, and this calculator will not invent a result for ages over 4. For older boys, use the CDC-based boys percentile calculator.

How UK-WHO percentiles work

The UK-WHO growth charts (RCPCH) adopted the WHO Child Growth Standards for ages 2 weeks to 4 years. That means a UK percentile in this window is mathematically identical to the WHO percentile — computed here with the published LMS method: look up the L, M, S parameters for the exact age, convert the measurement to a z-score, then to a percentile.

14 days – 24 months: recumbent length (lying down).
24 – 48 months: standing height (with the published ~0.7 cm method step preserved at 24 months).
Beyond 48 months: no result — the British 1990 tables aren't open data, and we never extrapolate.

Reading the result

The percentile tells you where the measurement falls among boys the same age in the reference — e.g. 75th percentile means taller than about 75% of peers. The z-score is the same information in standard-deviation units, useful for tracking over time. Neither is a grade or a diagnosis; a steady personal curve matters more than any single number.

Compare with other references in the boys height percentile calculator (CDC / WHO / UK-WHO switcher), see the curves on the boys growth chart, or estimate adult height with the child height predictor.

FAQ

UK boys percentile FAQs

What are the UK-WHO growth charts?

They are the growth charts used across the UK, published with the Royal College of Paediatrics and Child Health (RCPCH). From 2 weeks to 4 years of age they are based on the WHO Child Growth Standards — so UK percentiles in that window are computed from the WHO tables.

Why does this calculator stop at 4 years?

From age 4 the UK-WHO charts switch to the British 1990 reference, whose LMS tables are distributed under an MRC licence and are not open data — so we don't bundle them. Rather than invent numbers, the calculator honestly reports no result beyond 4 years. For older boys, use the CDC reference (ages 2–20).

Why does it start at 2 weeks, not birth?

On the paper UK-WHO charts, the first two weeks use UK90 pooled birth data, for which ordinary centile curves aren't published. Our UK percentiles therefore start at 14 days, matching what can actually be computed from published data.

Should I measure length or height?

Under 24 months, measure recumbent length (lying down); from 24 months, standing height — exactly as the UK-WHO charts do. The calculator handles the method change at 24 months the same way the published tables do.

Is my child's data stored?

No. All calculations run in your browser; nothing you enter is sent to a server or stored.

More height calculators

Boys Height Calculator

Quick height check for boys against CDC growth references.

Girls Height Calculator

Quick height check for girls against CDC growth references.

Baby Height Calculator

Length-for-age percentiles for babies 0–24 months (WHO).

Boys Height Percentile Calculator

Exact percentile + z-score with CDC / WHO / UK-WHO switcher.

Girls Height Percentile Calculator

Exact percentile + z-score with CDC / WHO / UK-WHO switcher.

Child Height Predictor

Predict adult height from parents' heights, with honest range.

Boys Growth Chart

Interactive CDC/WHO percentile curves — plot your own point.

Girls Growth Chart

Interactive CDC/WHO percentile curves — plot your own point.

Based on published growth references

Every percentile on this site is computed from official LMS tables — the same references pediatricians use. We never estimate outside the ages each reference covers.

CDC (US)

CDC 2000 Growth Charts, stature-for-age (National Center for Health Statistics)
Official source
WHO

WHO Child Growth Standards, length/height-for-age (WHO Multicentre Growth Reference Study, 2006)
Official source
UK-WHO

UK-WHO growth charts (RCPCH): ages 2 weeks-4 years follow the WHO Child Growth Standards
Official source