Knowledge
How much should a child weigh?
The honest answer is that there isn't one weight that suits all children of the same age. What constitutes a healthy weight depends on the child's height, sex, and – most importantly – how their weight has developed over time.
Why there is no simple weight chart
A tall child weighs more than a short child without being overweight, and children's bodies also change during their development. Therefore, healthcare professionals convert weight and height to BMI and compare the value with age and sex-adapted thresholds, known as iso-BMI.
If you want to calculate it yourself: BMI = weight in kilograms divided by height in metres squared. But remember that a single value doesn't determine if a child's weight is healthy.
Age-specific limits – 6 to 15 years
The table shows the BMI thresholds where overweight and obesity begin for each age, according to the international IOTF thresholds. To get a weight, the threshold is multiplied by the child's height squared.
| Age | Boys: overweight from | Girls: overweight from | Boys: obesity from | Girls: obesity from |
|---|---|---|---|---|
| 6 years | BMI 17.52 | BMI 17.33 | BMI 19.76 | BMI 19.62 |
| 7 years | BMI 17.88 | BMI 17.69 | BMI 20.59 | BMI 20.39 |
| 8 years | BMI 18.41 | BMI 18.28 | BMI 21.56 | BMI 21.44 |
| 9 years | BMI 19.07 | BMI 18.99 | BMI 22.71 | BMI 22.66 |
| 10 years | BMI 19.80 | BMI 19.78 | BMI 23.96 | BMI 23.97 |
| 11 years | BMI 20.51 | BMI 20.66 | BMI 25.07 | BMI 25.25 |
| 12 years | BMI 21.20 | BMI 21.59 | BMI 26.02 | BMI 26.47 |
| 13 years | BMI 21.89 | BMI 22.49 | BMI 26.87 | BMI 27.57 |
| 14 years | BMI 22.60 | BMI 23.27 | BMI 27.64 | BMI 28.42 |
| 15 years | BMI 23.28 | BMI 23.89 | BMI 28.32 | BMI 29.01 |
Example: An 11-year-old boy who is 1.45 metres tall reaches the overweight threshold at approximately 20.5 × 1.45 × 1.45 ≈ 43 kg. A taller child of the same age reaches the same threshold at a higher weight.
Important: The table is a classification aid, not an assessment of an individual child. Puberty, growth rate, and previous curve trends play a significant role.
Development over time is more important than current weight
Two children can weigh exactly the same and still require completely different assessments – one child has followed their curve for several years, the other has increased rapidly in a short time.
This is why healthcare professionals follow the child's growth curve instead of individual weighings. A rapidly rising curve may be worth noting even before any threshold has been passed.
Unsure about your child's weight?
Contact BVC for younger children, school health services for schoolchildren, or your healthcare centre. They can weigh, measure and assess the child's entire growth development – and offer advice based on your specific situation.
If you are concerned, it is always better to get in touch once too often than once too seldom.
Read about signs of overweight in children and when you should seek care
Do you work with childhood obesity in healthcare?
Evira makes it possible to follow the child's development between visits, with age-adapted thresholds built in.