yrs
Enter age between 2 and 20 years.
Decimals OK (e.g. 8.5 = 8 years 6 months)
CDC uses separate charts for boys and girls
lb
Enter a valid positive weight.
Child's current weight in pounds
Weight Percentile
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⚠️ Medical Disclaimer: Weight percentile alone does not determine healthy weight status in children. BMI-for-age (which accounts for height) is the preferred tool for assessing weight status. This calculator is educational only. Always discuss your child's growth with their pediatrician who tracks trends over time.
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Sources & Methodology
Weight percentile calculation based on CDC 2000 weight-for-age growth charts, the official standard used by US pediatricians for children and adolescents ages 2-20.
CDC — Clinical Growth Charts for Weight-for-Age (2000)
Official CDC 2000 weight-for-age growth charts for boys and girls ages 2-20, with median weight values used as the basis for all percentile calculations in this calculator
CDC — Development of the 2000 CDC Growth Charts (Pediatrics)
Peer-reviewed methodology publication describing the statistical LMS method, data sources, and construction of the CDC 2000 growth charts
Methodology: Weight converted to lbs if metric input used (kg x 2.2046). Percentile calculated by comparing entered weight to CDC 2000 50th percentile median values by age and sex. Z-score = (weight - median) / SD, where SD is approximated as 15% of median (reflecting the wider relative dispersion of weight compared to height). Normal CDF applied to Z-score to produce percentile. All percentile values are approximate. Average weights sourced from CDC 50th percentile published data.
⏱ Last reviewed: April 2026
How Child Weight Percentile Is Calculated
Weight percentile is one of the key metrics tracked at every well-child visit. This calculator uses the same CDC 2000 growth chart data that US pediatricians rely on. Unlike height, weight naturally has more variation between children of the same age and sex, which is why weight percentile alone is not used to diagnose weight problems — pediatricians use BMI-for-age (which combines weight and height) for that purpose. Weight-for-age is most useful for tracking growth velocity over time.
Why Weight Percentile Must Be Interpreted with Height
A child at the 80th percentile for weight may be perfectly healthy if they are also at the 80th percentile for height. The same weight percentile in a child at the 20th percentile for height would be concerning. This is precisely why pediatricians use BMI-for-age rather than weight-for-age alone to assess whether a child's weight is appropriate. Always interpret your child's weight percentile alongside their height percentile and BMI-for-age percentile.
CDC Average Weights by Age (50th Percentile)
| Age | Boys — Average Weight | Girls — Average Weight |
|---|---|---|
| 2 years | 27.5 lb (12.5 kg) | 26.5 lb (12.0 kg) |
| 4 years | 36.0 lb (16.3 kg) | 35.5 lb (16.1 kg) |
| 6 years | 45.5 lb (20.6 kg) | 44.0 lb (20.0 kg) |
| 8 years | 55.7 lb (25.3 kg) | 55.4 lb (25.1 kg) |
| 10 years | 70.5 lb (32.0 kg) | 71.6 lb (32.5 kg) |
| 12 years | 88.5 lb (40.1 kg) | 92.0 lb (41.7 kg) |
| 14 years | 112.0 lb (50.8 kg) | 108.0 lb (49.0 kg) |
| 16 years | 134.0 lb (60.8 kg) | 118.0 lb (53.5 kg) |
| 18 years | 148.0 lb (67.1 kg) | 125.0 lb (56.7 kg) |
Weight Gain Patterns by Age
- Ages 2-5 (preschool) — 4-5 lbs per year, steady growth
- Ages 6-10 (school age) — 5-7 lbs per year, fairly consistent
- Girls ages 8-13 (puberty) — 10-15 lbs per year at peak growth spurt
- Boys ages 10-16 (puberty) — 15-20 lbs per year at peak growth spurt
- After puberty — Weight gain slows; adult weight typically reached by late teens
💡 Key Insight: Weight percentile is most meaningful when tracked over multiple visits. A child who stays at the same percentile for years is growing normally, even if that percentile is low or high. What concerns pediatricians most is a sudden change — like jumping from the 40th to the 75th percentile — which can indicate a shift in diet, activity, or health status that warrants investigation.
Frequently Asked Questions
Weight percentile compares your child's weight to other children the same age and sex. A child at the 60th percentile weighs more than 60% of children their age and sex. The CDC publishes separate weight-for-age growth charts for boys and girls ages 2-20.
Average weight for a 10-year-old boy is approximately 70.5 pounds (32.0 kg). For a 10-year-old girl, the average is approximately 71.6 pounds (32.5 kg). Girls weigh slightly more than boys at age 10, reflecting earlier puberty onset.
A healthy weight falls between the 5th and 85th percentile for weight-for-age AND produces a BMI-for-age between the 5th and 85th percentile. Weight alone is not sufficient because height must be considered. Always use weight-for-age alongside BMI-for-age percentile.
Average weight for a 5-year-old boy is approximately 40.5 pounds (18.4 kg). For a 5-year-old girl, the average is approximately 39.6 pounds (18.0 kg). Weight gain during preschool and school years is typically 4 to 7 pounds per year.
Average weight for a 12-year-old boy is approximately 88.5 pounds (40.1 kg). For a 12-year-old girl, the average is approximately 92.0 pounds (41.7 kg). Girls typically weigh more than boys at 12 due to earlier puberty, but boys catch up by mid-adolescence.
No. Weight percentile alone does not determine healthy weight because it does not account for height. A tall child may have a high weight percentile but be completely healthy. Pediatricians use BMI-for-age (weight and height combined) to assess weight status properly.
Below the 5th percentile may indicate underweight or poor nutrition, but can also be normal for small-framed children with similarly low height percentiles. A pediatrician should evaluate children consistently below the 5th percentile or who show a sudden drop in their percentile ranking.
Typical gains: toddlers 4-5 lbs per year, school age 5-7 lbs per year, puberty peak girls 10-15 lbs per year, puberty peak boys 15-20 lbs per year. Growth slows after puberty is complete.
Average weight for an 8-year-old boy is approximately 55.7 pounds (25.3 kg). For an 8-year-old girl, the average is approximately 55.4 pounds (25.1 kg). Boys and girls weigh approximately the same at age 8 before puberty causes divergence.
The CDC 2000 weight-for-age growth charts show weight percentile curves from ages 2-20 for boys and girls separately. Based on a nationally representative US sample, they are the standard reference used by pediatricians throughout the United States for tracking child weight over time.
Consult your pediatrician if your child is consistently below the 5th or above the 95th percentile, their percentile changes by 15 or more points between visits, they experience unexplained weight loss, or their weight gain stops for an extended period. A single unusual reading is rarely cause for alarm.
Weight-for-age compares weight without accounting for height. BMI-for-age calculates BMI (weight divided by height squared) and compares it to peers of the same age and sex. BMI-for-age is preferred for assessing weight status because it accounts for height. Weight-for-age is best for tracking growth velocity trends over time.
Multiply kilograms by 2.2046 to get pounds. Examples: 20 kg = 44.1 lbs, 30 kg = 66.1 lbs, 40 kg = 88.2 lbs. To convert pounds to kg, multiply by 0.4536. This calculator accepts both pounds and kilograms as input.
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