Child · Growth

Child & Teen Growth Chart

Height-for-age and weight-for-age percentile and z-score for ages 2 to 20 using the CDC 2000 LMS growth reference. Together with our 0-24 mo (WHO) and BMI-for-age calculators, covers the full birth-to-20 growth picture.

Last reviewed 25 May 2026

Height & weight percentile (CDC LMS)

Child & teen growth chart — ages 2-20

Units

Sex assigned at birth

y
mo
cm
kg
Enter age, height and weight to see CDC percentiles.

How to use this calculator

Pick metric or imperial units, sex assigned at birth, age in years and months, height, and weight. The calculator returns the CDC percentile and z-score for both height-for-age and weight-for-age independently. For BMI-for-age (which picks up overweight and obesity), use the dedicated Child & Teen BMI calculator.

The reference data

We use the CDC 2000 Growth Charts (Kuczmarski 2002), which provide smoothed LMS parameters for stature-for-age and weight-for-age at half-month intervals from 24 months to 240 months, separately for boys and girls. The LMS framework (Cole 1990) handles the skewness of growth distributions with three age-specific parameters: L (skewness), M (median), S (coefficient of variation).

How the z-score is calculated

z = ((value / M) ^ L − 1) / (L × S)   if L ≠ 0
z = ln(value / M) / S                  if L = 0

Percentile = Φ(z), where Φ is the standard normal cumulative distribution function. We use the Abramowitz-Stegun 7.1.26 erf approximation (error < 1.5 × 10-7) so the percentile is accurate to better than 0.0002 % in absolute terms. For stature-for-age, CDC convention sets L = 1 throughout, so the formula simplifies to z = (height/M − 1) / S.

How to interpret the percentile

  • 3rd – 97th percentile — typical range. About 94 % of the reference population sits here.
  • Below 3rd or above 97th — outside the typical range. Worth a paediatric review at the next visit; not automatically a problem.
  • Crossing two major percentile lines (75th → 25th, 50th → 10th, etc.) sustained over visits — recognised growth-referral trigger. Bring previous heights and weights.
  • Below 2nd percentile and not growing along a curve — warrants endocrine evaluation (short stature workup); causes include growth hormone deficiency, hypothyroidism, coeliac disease, chronic illness, syndromic causes.

Trajectory > single point

A single measurement is a snapshot; the growth chart is a movie. Children should track along their own curve, not jump between percentiles. The paediatric concern is not where you sit on the chart but whether you are MOVING ACROSS curves. Bring measurement history to visits.

Inheritance and the parental adjustment

Adult height is ~80 % heritable. A useful mental check is mid-parental height:

  • Boy: (father’s height + mother’s height + 13 cm) / 2
  • Girl: (father’s height + mother’s height − 13 cm) / 2

With ±10 cm 95 % confidence. A child whose current trajectory projects to an adult height more than 2 SD below mid-parental height deserves endocrine evaluation. Use our Child Height Predictor for the calculation with confidence intervals.

Limitations

  • The CDC chart is a US population reference. International populations may have different distributions, especially South / East Asian ancestries where weight-for-age distributions sit lower at the same height.
  • Standard charts don’t apply to syndromic conditions (Turner, Down, Noonan, Marfan, etc.) — use condition-specific charts.
  • Preterm-born children: under age 2, plot to corrected (post-term) age; from age 2 onward, plot to chronological age.
  • Reference is now ~25 years old. Adult population BMI has shifted right since publication; for overweight/obesity assessment use the AAP 2023-aware Child & Teen BMI calculator with Class 2 / 3 bands.

Sources

  • Kuczmarski RJ, Ogden CL, Guo SS, et al. 2000 CDC Growth Charts for the United States: Methods and Development. Vital Health Stat 2002;11(246).
  • Cole TJ. The LMS method for constructing normalized growth standards. Eur J Clin Nutr 1990;44:45-60.
  • WHO Multicentre Growth Reference Study Group. WHO Child Growth Standards based on length/height, weight and age. Geneva, 2006.
  • de Onis M, Onyango AW, Borghi E, et al. Development of a WHO growth reference for school-aged children and adolescents. Bull World Health Organ 2007;85:660-7. (For the 5-19 yr WHO extension)
  • Silventoinen K, Sammalisto S, Perola M, et al. Heritability of adult body height: a comparative study of twin cohorts in eight countries. Twin Res 2003;6:399-408.

Frequently asked questions

Why CDC and not WHO for ages 2-20?
Because the WHO Multicentre Growth Reference Study only published growth standards from birth to 5 years (extended to 19 years via WHO 2007 references). The CDC 2000 Growth Charts cover ages 2-20 using US population data, and remain the standard in the US for this age range. WHO and CDC agree closely from 2-5 years where they overlap. For under-2-year-olds, the WHO Growth Standards are preferred internationally (and recommended by AAP); use the Baby Growth Percentile calculator for that age.
What's the difference between a z-score and a percentile?
They convey the same information in different units. A z-score is the number of standard deviations from the population median (positive = above, negative = below). A percentile is the percentage of the reference population at or below this value. z = 0 ↔ 50th percentile; z = +1 ↔ ~84th percentile; z = +2 ↔ ~97.7th percentile; z = -2 ↔ ~2.3rd percentile. Z-scores are more useful at the extremes (a z of +3.5 is far more informative than 'above the 99th percentile') and in research; percentiles are easier for families to understand.
My child's percentile dropped — should I worry?
Maybe. A single drop within the normal range can reflect measurement variation, recent illness, or a growth pause that the child will catch up from. CROSSING TWO MAJOR PERCENTILE LINES (e.g. 75th → 25th, or 50th → 10th) over a sustained period is a recognised endocrine / growth referral trigger — the child's growth trajectory has shifted in a way that warrants investigation. The AAP recommends paediatric review for any sustained percentile crossing of this magnitude, particularly if velocity has fallen (the child is growing slower than expected for age).
Why is height-for-age more 'inherited' than weight-for-age?
Adult height is roughly 80 % heritable in twin and adoption studies (Silventoinen 2003); polygenic, dependent on hundreds of genetic variants. Childhood weight is more environmental — nutrition, activity, family eating patterns — though there's still a substantial genetic component (~40-70 %). Practical implication: a child tracking the 25th percentile for height when both parents are short is reassuring; a child tracking the 95th percentile for weight when both parents are at the 50th is more notable.
Are the CDC charts still valid after 25 years?
For overall growth trajectories, yes — the chart structure (LMS curves) is robust and the methodology is sound. However, the US population has gotten heavier since the 2000 chart was published, so an 'average' BMI by today's CDC chart is actually less healthy than the 50th percentile would suggest. This is why the AAP 2023 Clinical Practice Guideline introduced Class 2 and Class 3 obesity bands beyond the 95th percentile — to capture the rightward shift of the population distribution. For height-for-age, secular trends in adult height have largely plateaued in high-income countries, so the chart remains representative.
What's 'mid-parental height' and how does it relate?
An estimate of a child's expected adult height based on parental heights. For a boy: (father's height + mother's height + 13 cm) / 2. For a girl: (father's height + mother's height - 13 cm) / 2. The estimate has a 95 % CI of roughly ±10 cm. A child tracking well below the trajectory predicted by mid-parental height (>2 SD below) deserves endocrine evaluation. Try our dedicated Child Height Predictor calculator for the calculation with confidence intervals.
What about Turner / Down / Noonan syndrome charts?
These conditions have their own dedicated growth references because children with these conditions follow different trajectories. Turner syndrome girls grow along the Lyon-Bostock or Sybert Turner-specific chart; Down syndrome children along the Zemel 2015 chart; Noonan syndrome along Witt 1986. The standard CDC chart is not appropriate for these conditions. If your child has a known genetic / syndromic diagnosis, ask your paediatric endocrinologist for the appropriate condition-specific chart.

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