BMI (Body Mass Index) Chart by Age
Find out what your BMI means. Select your value to see a detailed breakdown with health implications and practical advice.
BMI (Body Mass Index) - Male
| Age Group | Very Poor | Poor | Fair | Good | Excellent | Superior |
|---|---|---|---|---|---|---|
| 20-29 years | 30+ | 27.5-30 | 24.9-27.5 | 22-24.9 | 20-22 | < 20 |
| 30-39 years | 30+ | 27.5-30 | 24.9-27.5 | 22-24.9 | 20-22 | < 20 |
| 40-49 years | 30+ | 27.5-30 | 24.9-27.5 | 22-24.9 | 20-22 | < 20 |
| 50-59 years | 30+ | 27.5-30 | 24.9-27.5 | 22-24.9 | 20-22 | < 20 |
| 60-69 years | 30+ | 27.5-30 | 24.9-27.5 | 22-24.9 | 20-22 | < 20 |
| 70+ years | 30+ | 27.5-30 | 24.9-27.5 | 22-24.9 | 20-22 | < 20 |
| kg/m² | ||||||
BMI (Body Mass Index) - Female
| Age Group | Very Poor | Poor | Fair | Good | Excellent | Superior |
|---|---|---|---|---|---|---|
| 20-29 years | 30+ | 27.5-30 | 24.9-27.5 | 22-24.9 | 20-22 | < 20 |
| 30-39 years | 30+ | 27.5-30 | 24.9-27.5 | 22-24.9 | 20-22 | < 20 |
| 40-49 years | 30+ | 27.5-30 | 24.9-27.5 | 22-24.9 | 20-22 | < 20 |
| 50-59 years | 30+ | 27.5-30 | 24.9-27.5 | 22-24.9 | 20-22 | < 20 |
| 60-69 years | 30+ | 27.5-30 | 24.9-27.5 | 22-24.9 | 20-22 | < 20 |
| 70+ years | 30+ | 27.5-30 | 24.9-27.5 | 22-24.9 | 20-22 | < 20 |
| kg/m² | ||||||
What is BMI (Body Mass Index)?
Body Mass Index (BMI) is a simple calculation based on your height and weight (weight in kg divided by height in meters squared). It is the most widely used screening tool for categorizing weight status in adults. The WHO classifies BMI into four main categories: underweight (<18.5), normal weight (18.5-24.9), overweight (25-29.9), and obese (30+). While BMI is useful for population-level health assessment, it has important limitations at the individual level. It cannot distinguish between muscle mass and fat mass, meaning a muscular athlete and a sedentary person can have the same BMI with very different body compositions. For a more accurate picture of body composition, consider tracking body fat percentage instead.
Measuring with Apple Watch
Apple Watch does not measure weight or BMI directly. To track BMI over time, the most convenient method is a smart scale that automatically logs your weight to Apple Health. Popular options include Withings Body+, Renpho Smart Scale, and Eufy Smart Scale. These devices calculate BMI from your weight and height and sync the data wirelessly. Vita can import weight and BMI data from Apple Health to track your trends over time. For the most consistent readings, weigh yourself at the same time each day (ideally morning, after using the bathroom, before eating) and let the smart scale handle the BMI calculation.
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Frequently Asked Questions
What is a healthy BMI?
According to the WHO, a healthy BMI for adults is 18.5-24.9, regardless of age or gender. BMI below 18.5 is underweight, 25-29.9 is overweight, and 30+ is obese. Within the healthy range, research suggests that BMI 20-24 is associated with the lowest health risks.
Does BMI change with age?
Your BMI changes as your weight changes, but the WHO classification ranges remain the same for all adults. Body composition does shift with age: older adults tend to have more fat and less muscle at the same BMI compared to younger adults. This is one reason why BMI becomes less accurate with age and why body fat percentage is a more informative metric.
Why is BMI the same for men and women?
The WHO uses universal BMI ranges because BMI was designed as a simple population screening tool, not a precise individual diagnostic. While men and women differ in body composition at the same BMI (women naturally carry more essential fat), the BMI thresholds for health risk apply broadly across both sexes. For individual assessment, body fat percentage provides a gender-specific view.
Is BMI accurate for athletes?
BMI is often inaccurate for athletes and highly muscular individuals. Since muscle weighs more than fat by volume, a lean athlete with significant muscle mass can have a BMI in the overweight range (25-30) while having excellent body composition. If you train regularly, body fat percentage is a far more accurate measure of your health than BMI.
What is better than BMI?
Body fat percentage is the most widely recommended alternative, as it directly measures fat versus lean mass. Waist circumference and waist-to-hip ratio are also valuable because they reflect visceral fat, which is the type most strongly linked to health risks. DEXA scans provide the most complete picture of body composition. For most people, combining BMI with waist circumference gives a much better assessment than BMI alone.
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