⚖️ BMI Calculator
Calculate your Body Mass Index and see where you fall on the BMI scale.
Your Measurements
Your BMI
0
UnderweightNormalOverweightObese
Category
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Healthy Weight Range
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Weight to Lose/Gain
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Prime BMI
18.5–24.9
What is BMI?
Body Mass Index (BMI) is a simple screening tool that uses your height and weight to estimate body fat. It's widely used by healthcare professionals as a first screening for weight-related health risks.
BMI = weight (kg) / height (m)²
or in imperial: BMI = 703 × weight (lbs) / height (inches)²
or in imperial: BMI = 703 × weight (lbs) / height (inches)²
BMI Categories (WHO Standard)
| BMI Range | Category | Health Risk |
|---|---|---|
| Below 18.5 | Underweight | Increased risk (malnutrition) |
| 18.5–24.9 | Normal weight | Lowest risk |
| 25.0–29.9 | Overweight | Moderately increased |
| 30.0–34.9 | Obese (Class I) | High risk |
| 35.0–39.9 | Obese (Class II) | Very high risk |
| 40+ | Obese (Class III) | Extremely high risk |
Limitations of BMI
- Doesn't measure body fat directly — a muscular athlete may have a "overweight" BMI despite low body fat
- Doesn't account for fat distribution — waist circumference is often a better predictor of metabolic risk
- Age and sex differences — older adults naturally have more body fat; women have more fat than men at the same BMI
- Ethnicity variations — health risks may begin at lower BMIs for Asian populations
Is BMI accurate for athletes and bodybuilders? +
No. Muscle is denser than fat, so athletes often have a high BMI despite having very low body fat. For example, many NFL running backs have BMIs in the "overweight" or "obese" range. Better metrics for athletes include body fat percentage via DEXA scan or hydrostatic weighing.
What's a healthy BMI for women vs. men? +
The standard BMI categories (18.5–24.9 for normal) apply to both men and women. However, women naturally carry more body fat than men at the same BMI. Some researchers suggest women's "healthy" BMI ceiling may be slightly different, but the WHO standard categories remain the most widely used.