SuperCalc

BMI Chart by Age

While the standard BMI formula doesn't change with age, its interpretation does. Younger adults tend to have more muscle mass, so a BMI of 26 might reflect fitness. Older adults lose muscle and gain fat (even at stable weight), so the same BMI may indicate higher body fat percentage. Some researchers suggest a slightly higher healthy range (23–28) for adults over 65. Use the calculator below, then consider your age when interpreting the result.

BMI Calculator

Enter your height and weight to calculate your Body Mass Index.

cm
kg

BMI Categories

WHO classification of Body Mass Index ranges.

CategoryBMI Range
Underweight
< 18.5
Normal
18.5 – 24.9
Overweight
25 – 29.9
Obese I
30 – 34.9
Obese II
35 – 39.9
Obese III
40+

Frequently Asked Questions

Does BMI change with age?
The formula doesn't change, but body composition does. After about age 30, adults lose roughly 3–5% of muscle mass per decade (sarcopenia). This means your body fat percentage can increase even if your weight and BMI stay the same. By age 70, a BMI of 25 may represent significantly more fat than at age 25.
What is a healthy BMI for someone over 65?
Research suggests slightly higher BMIs (23–28) may be protective in older adults, reducing risks from frailty, falls, and illness recovery. Being slightly 'overweight' by standard BMI categories appears to confer a survival advantage after age 65 — the so-called 'obesity paradox.'
Should children use adult BMI categories?
No. Children and teens (ages 2–19) should use BMI-for-age percentile charts from the CDC or WHO. Their body composition changes too rapidly during growth for fixed adult cutoffs to be meaningful. A pediatrician can plot your child's BMI against age-appropriate norms.

Medical disclaimer: BMI is a screening tool, not a medical diagnosis. It does not measure body fat directly and does not account for muscle mass, bone density, age, sex, or ethnicity. Consult a healthcare provider for personalized health advice.

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