BMI Calculator — Body Mass Index
Check your WHO category, healthy weight range and ideal weight instantly
What is BMI?
BMI (Body Mass Index) is a measure that relates weight to height to classify a person within healthy weight ranges. It is calculated by dividing weight in kg by the square of height in meters. While it's a useful screening tool, it has limitations: it doesn't distinguish between muscle mass and fat. Also read why BMI vs body fat percentage don't measure the same thing.
How to interpret your BMI
Enter your weight and height. The result shows you which WHO category you fall into, your healthy weight range for your height, and ideal weight according to three different formulas (Devine, Robinson and Miller).
BMI categories according to WHO
| Category | BMI | Health risk |
|---|---|---|
| Underweight | < 18.5 | Moderate (malnutrition, osteoporosis) |
| Normal weight | 18.5 – 24.9 | Minimal |
| Overweight | 25 – 29.9 | Increased |
| Obese class I | 30 – 34.9 | Moderate |
| Obese class II | 35 – 39.9 | Severe |
| Obese class III | ≥ 40 | Very severe |
Health risks by BMI
Malnutrition, bone density loss (osteoporosis), anemia, weakened immune system and cardiac problems in severe cases.
Minimal risk. Maintain weight with a balanced diet and regular physical activity to preserve this range long-term.
Increased risk of hypertension, high cholesterol, type 2 diabetes and sleep apnea. A 5–10% weight loss already significantly reduces risk.
Moderate-high risk: type 2 diabetes, cardiovascular disease, fatty liver, osteoarthritis and certain cancers (colon, breast, endometrium).
High risk: metabolic syndrome, heart failure, deep vein thrombosis. Medical intervention is recommended.
Very high risk: reduced life expectancy, severe sleep apnea, reduced mobility. Bariatric surgery may be required.
FAQ
1Is BMI a reliable measure?
BMI is useful for population analysis but has individual limitations. It doesn't distinguish between fat and muscle: an athlete with a lot of muscle mass can have an 'overweight' BMI while being completely healthy.
2What is the ideal BMI?
According to WHO, the normal range is 18.5-24.9. Some studies suggest the optimal longevity range is 22-25.
3How can I reduce my BMI?
BMI is reduced mainly through body fat loss via moderate caloric deficit combined with strength training to preserve muscle mass.
4Does BMI work the same for all ethnicities?
No. People of Asian descent have higher risk of metabolic diseases at lower BMIs, so some organizations recommend lower thresholds for this population.
Related tools
TDEE Calculator
Basal metabolic rate and daily calories by activity level
Calorie Deficit
Personalized weight-loss plan with estimated date
Macro Calculator
Exact split of protein, carbohydrates and fat
Recipe Calories
Exact calories and macros for any homemade recipe
Food Calories
Nutritional data for 200+ foods per 100 g