Height and Weight Calculator by Age
Why Height and Weight Percentiles Matter
A child's raw height and weight numbers mean relatively little on their own — what matters is how those measurements compare to other children of the same age and sex. A 10-year-old boy who is 145 cm tall could be average, tall, or short depending on where that falls relative to peers. Percentiles answer that question precisely.
The CDC 2000 growth reference charts, used by pediatricians throughout the United States, represent the height and weight distribution of a large nationally representative sample of American children. They are the standard tool for tracking growth in children aged 2 to 20 in the US clinical setting.
What a percentile means: A child at the 60th percentile for height is taller than 60% of children the same age and sex, and shorter than the remaining 40%. Being at the 60th versus the 40th percentile carries no clinical significance — what matters is whether a child is tracking consistently on their own curve over time, not their absolute percentile rank.
How This Calculator Works
Match Age & Sex
Age and sex are matched to the appropriate CDC 2000 LMS parameter table — separate charts exist for boys and girls for both height-for-age and weight-for-age.
Interpolate LMS Values
L (skewness), M (median), and S (coefficient of variation) parameters are linearly interpolated between the two nearest age data points for precision.
Compute Z-Score
A z-score is derived from the measurement using the Box-Cox LMS formula: z = [(X/M)^L − 1] / (L × S). This accounts for the skewed distribution of weight data.
Convert to Percentile
The z-score is converted to a percentile using the standard normal CDF. BMI is calculated from height and weight, then evaluated against the CDC BMI-for-age chart separately.
CDC Height and Weight Reference Ranges by Age
The tables below show approximate 5th, 50th, and 95th percentile values for height and weight from the CDC 2000 growth charts. These are reference values — individual healthy children span the full range.
Boys — Height (cm) and Weight (kg)
| Age | Ht 5th | Ht 50th | Ht 95th | Wt 5th | Wt 50th | Wt 95th |
|---|---|---|---|---|---|---|
| 2 yrs | 82.3 | 87.5 | 93.0 | 10.5 | 12.6 | 15.3 |
| 4 yrs | 97.3 | 103.3 | 109.5 | 14.0 | 16.7 | 20.7 |
| 6 yrs | 110.0 | 116.1 | 122.4 | 17.6 | 21.4 | 27.1 |
| 8 yrs | 120.5 | 127.0 | 133.9 | 21.8 | 27.0 | 35.7 |
| 10 yrs | 129.7 | 137.5 | 145.5 | 26.6 | 34.0 | 47.2 |
| 12 yrs | 138.0 | 149.1 | 160.0 | 32.2 | 42.7 | 62.7 |
| 14 yrs | 151.8 | 163.8 | 174.5 | 41.2 | 55.8 | 79.7 |
| 16 yrs | 162.0 | 173.5 | 182.4 | 51.4 | 66.3 | 91.9 |
| 18 yrs | 165.1 | 176.5 | 185.4 | 57.0 | 72.5 | 99.4 |
| 20 yrs | 165.5 | 177.0 | 186.0 | 59.0 | 75.2 | 103.0 |
Girls — Height (cm) and Weight (kg)
| Age | Ht 5th | Ht 50th | Ht 95th | Wt 5th | Wt 50th | Wt 95th |
|---|---|---|---|---|---|---|
| 2 yrs | 81.0 | 86.5 | 91.8 | 10.1 | 12.1 | 14.7 |
| 4 yrs | 96.0 | 102.0 | 108.4 | 13.5 | 16.2 | 20.2 |
| 6 yrs | 108.4 | 114.6 | 121.2 | 17.1 | 20.7 | 26.7 |
| 8 yrs | 119.2 | 126.0 | 133.2 | 21.4 | 26.6 | 35.7 |
| 10 yrs | 129.6 | 137.6 | 146.5 | 26.6 | 34.5 | 49.4 |
| 12 yrs | 141.0 | 150.0 | 159.5 | 33.8 | 44.7 | 65.8 |
| 14 yrs | 149.0 | 158.0 | 166.8 | 42.5 | 55.0 | 79.2 |
| 16 yrs | 151.2 | 160.2 | 169.2 | 47.5 | 60.1 | 86.5 |
| 18 yrs | 152.0 | 161.2 | 170.2 | 49.7 | 62.5 | 90.2 |
| 20 yrs | 152.2 | 161.5 | 170.7 | 50.5 | 63.9 | 92.4 |
Understanding Your Child's Results
The CDC defines the following BMI-for-age categories for children and teens aged 2 to 20:
Height and weight percentiles can diverge significantly — and that is normal. A child at the 80th percentile for height and the 40th for weight is proportionately lean for their frame. A child at the 30th for height and 70th for weight has a higher weight relative to their height — which is what BMI-for-age captures. Always interpret height and weight percentiles together, not in isolation.
When to Talk to Your Pediatrician
Frequently Asked Questions
What is a normal height percentile for a child?
Any height percentile between the 3rd and 97th is considered within the normal statistical range on CDC growth charts. There is no single "ideal" percentile — a child at the 10th percentile who has tracked there consistently from age 2 is growing normally on their own curve. What draws clinical attention is not an absolute percentile but a shift in percentile across visits, particularly crossing two or more major lines (5th, 10th, 25th, 50th, 75th, 90th, 95th) without an obvious explanation.
Is BMI-for-age the same as adult BMI?
No. Adult BMI uses fixed cutoffs — 18.5, 25, and 30 — that apply to all adults regardless of age or sex. For children and teens aged 2 to 20, BMI must be evaluated using age- and sex-specific percentiles because body fatness changes significantly with age and differs between boys and girls. A BMI of 22 means something very different for a 10-year-old than for a 30-year-old. This is why pediatricians use BMI-for-age percentiles rather than adult BMI categories for anyone under 20.
My child is at the 25th percentile for height — should I be worried?
No. The 25th percentile means your child is taller than 25% of children their age and sex — it is within the normal range. If your child has consistently tracked near the 25th percentile since early childhood, this is simply their growth pattern, likely reflecting their genetic height potential. Concern would arise if they were previously tracking at the 60th percentile and recently fell to the 25th — that shift, not the absolute value, is what matters clinically.
Which growth chart does this calculator use?
This calculator uses the CDC 2000 growth reference charts for children and teens aged 2 to 20 years in the United States. These are the charts used by American pediatricians for well-child visits. For children under 2, the WHO Child Growth Standards are typically used instead — those are based on a prospective international cohort of optimally nourished children and are available in a separate calculator on this site.
Can I use this calculator for a child who was born premature?
For premature children, age should be corrected for gestational age when plotting on growth charts — particularly before age 2. Corrected age is calculated as chronological age minus the number of weeks born early. For example, a child who was born 8 weeks early and is now 6 months old should be plotted at 4 months corrected age. Most pediatricians stop correcting for prematurity by age 2 for most children, though those born before 28 weeks may need correction until age 3. Discuss the appropriate approach with your child's pediatrician.
