Calculating a person’s BMI is a reliable indicator of whether they are overweight or obese. To calculate a child’s BMI, you need their weight and height, and there are two formulas depending on the units used. Interpreting the result is more complicated for children, as age and growth history must be taken into account. A BMI chart is provided to measure children’s BMI and provide percentile indicators that take into account age and gender. If concerned about a child’s weight, talk to a pediatrician or GP.
Calculating a person’s Body Mass Index (BMI), which is a number obtained from a mathematical equation that takes into account a person’s height and weight, has been shown to be a reliable indicator for screening for weight that could lead to health problems. When calculating an adult’s BMI, the number becomes an indicator of whether a person is overweight or obese. Similarly, calculating children’s BMI results in a similar indicator of whether a child is overweight or obese, but also serves as an indicator of the risk of becoming overweight or obese.
To calculate children’s BMI, you must first have the variables to plug into the equation. You must have the weight and height of the child. There are two formulas for calculating children’s BMI: one that uses kilograms and meters, and one that uses pounds and inches. They are not the same formula, but if it works correctly it will calculate the same answer.
If you are calculating children’s BMI based on their weight and height in kilograms and meters, the formula is BMI = weight (kg) divided by the child’s height in meters squared. For example, take a child who weighs 45.5 kilograms and is 1.5 meters tall. To calculate the example child’s BMI, you would first multiply itself 1.5 times itself (1.5 X 1.5) to get 2.25. Then divide your weight (100lbs) by 2.25 to get a BMI of 20.2. (Rounds numbers beyond the decimal point in the calculation to the nearest tenth.)
When measuring weight and height in pounds and inches, the formula for calculating children’s BMI is weight in pounds times 703 divided by height in inches squared. Taking the example above, the child’s weight in pounds is 100 and his height in inches is 59 inches (or just under five feet). Taking the weight of 100 pounds and multiplying it by 703 we get 70,300. Multiplying the example height by itself equals 3481. Dividing 70,300 by 3481 gives us a calculated BMI answer of 20.2 when rounded to the nearest tenth.
Calculating children’s BMI is much easier than interpreting the answer because, unlike adults, children aren’t done growing. This means that their age must be taken into consideration as well as their growth chart history. A BMI chart is provided to measure children’s BMI and provide percentile indicators that take into account age and gender. To help interpret children’s BMI, you can graph information on a gender-adjusted BMI chart that indicates mean percentiles.
For example, an eighteen-year-old boy with a BMI of 20.2 would fall just below the 25th percentile, meaning that at least 75% of boys his age would have a BMI above him. Conversely, if a nine-year-old has the same BMI of 20.2, she would be in the 95th percentile, meaning 95 percent of children have a lower BMI than her. In the latter example, this child would most likely be considered overweight since a BMI that falls above the 90th percentile is an indicator of overweight. The exception to this might be if a child’s height, weight, and BMI have remained consistently in the same percentile range (high or low) since the beginning of growth. This could be the case for a child with unusual muscle mass or above average height.
With or without the presence of a gender-appropriate BMI graph, BMI calculations for children can still be difficult to interpret. As a rule of thumb, children’s BMI should not be based on adult calculations as an ideal adult BMI is between 19.1 and 25.8, which may or may not be ideal for a child depending on their age, weight, height and growth story.
If you are concerned about your child’s weight, talk to your pediatrician or GP. They can calculate and interpret your child’s overall physical development, assess risk, and intervene if necessary.
Protect your devices with Threat Protection by NordVPN
