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The BMI calculator checks if your weight is healthy. Enter height and weight to get BMI, TDEE and BMR using the Mifflin-St Jeor formula.
BMI (Body Mass Index) is calculated using the formula: weight [kg] ÷ height² [m]. Example: a person weighing 75 kg and 175 cm tall has BMI = 75 ÷ (1.75²) = 75 ÷ 3.0625 = 24.5 — a healthy result.
| BMI | Category | Health risk |
|---|---|---|
| Below 18.5 | Underweight | Elevated |
| 18.5 – 24.9 | Normal weight | Minimal |
| 25.0 – 29.9 | Overweight | Moderate |
| 30.0 – 34.9 | Obese class I | High |
| Above 35 | Obese class II–III | Very high |
BMI alone is not enough — it is equally important to know how many calories you need each day. The calculator computes your TDEE (Total Daily Energy Expenditure) using the Mifflin-St Jeor formula, taking into account gender, age, height, weight and activity level.
BMI does not distinguish between fat and muscle tissue. An athlete with high muscle mass may have a BMI of 27 (overweight) despite excellent fitness. It is worth supplementing it with waist circumference (Extended tab) and the macronutrient calculator.
Is BMI reliable? For most adults yes — but not for athletes, pregnant women and people over 65.
What is the ideal BMI? WHO recommends the range 18.5–24.9. Research shows the lowest mortality falls in the BMI 20–25 range.
How fast can I lose weight safely? A safe rate is 0.5–1 kg per week. Check the progress chart to see how long it will take to reach your goal.
BMI (Body Mass Index) is a value derived from a person's weight and height. The World Health Organization (WHO) uses it as a standard screening tool to classify adults into weight categories. It correlates with health risks including type 2 diabetes, cardiovascular disease and hypertension — though it is a screening tool, not a diagnosis.
BMI = weight [kg] ÷ height² [m]
Example: 75 kg, 175 cm → BMI = 75 ÷ (1.75²) = 24.5 — healthy range.
| BMI Range | Category | Health Risk |
|---|---|---|
| Below 18.5 | Underweight | Elevated |
| 18.5 – 24.9 | Normal weight | Minimal |
| 25.0 – 29.9 | Overweight | Moderate |
| 30.0 – 34.9 | Obese (Class I) | High |
| 35.0 – 39.9 | Obese (Class II) | Very high |
| 40 and above | Obese (Class III) | Extremely high |
BMI tells you where you are. TDEE (Total Daily Energy Expenditure) tells you what to eat to change or maintain your weight. This calculator uses the Mifflin-St Jeor equation — the most validated formula in nutrition science.
BMI doesn't distinguish fat from muscle. A bodybuilder may register as "overweight" despite low body fat. For older adults, BMI may underestimate risk. Asian populations carry metabolic risk at lower BMI values. Combine BMI with waist circumference and other markers for a full picture.