Body Mass Index
Enter your height and weight to find your BMI and healthy weight range.
Your BMI
22.5
Normal weight
BMI is a rough screening figure, not a diagnosis — it doesn't distinguish muscle from fat.
Body Mass Index (BMI) is a quick screening tool that estimates whether your weight is healthy for your height. This free calculator instantly shows your BMI number, tells you if you're underweight, normal, overweight, or obese, and helps you understand what it means for your health.
BMI is a ratio of your weight in kilograms to your height in metres squared (kg/m²). It's a screening tool used by doctors and health professionals worldwide to assess whether someone's weight falls into a healthy range for their height. BMI doesn't measure body fat directly—athletes with muscle mass may score higher—but it's useful for spotting health risks at the population level.
The calculator divides your weight (in kg) by your height (in metres) squared. Enter your measurements in either metric (kg/m) or imperial (lbs/inches) units, and the tool instantly converts and computes your BMI, then categorises it into one of five standard ranges: Underweight (<18.5), Normal weight (18.5–24.9), Overweight (25–29.9), Obese class I (30–34.9), and Obese class II (≥35).
BMI = weight (kg) ÷ [height (m)]²Weight is your body mass in kilograms; height is your standing height in metres. Square the height first, then divide weight by that result. For imperial units (pounds and inches), multiply the result by 703 after dividing weight by height squared.
| Input | Result | Notes |
|---|---|---|
| Weight: 70 kg, Height: 1.75 m | BMI = 22.9 (Normal weight) | Falls within the healthy range of 18.5–24.9; no weight-related health action needed. |
| Weight: 90 kg, Height: 1.70 m | BMI = 31.0 (Obese class I) | Exceeds 30; associated with increased risk of heart disease, type 2 diabetes, and joint strain. |
| Weight: 55 kg, Height: 1.65 m | BMI = 20.2 (Normal weight) | Healthy range; generally lower risk for weight-related chronic diseases. |
Yes. BMI 25–29.9 is classified as overweight. Normal weight is 18.5–24.9. However, if you're muscular or athletic, your BMI may be naturally higher; consult a healthcare provider.
The ideal range is 18.5–24.9 (normal weight). This range is associated with the lowest risk of weight-related diseases in the general population, though individual needs vary.
Yes. BMI doesn't account for muscle mass, bone density, age, or ethnicity. Athletes and older adults may have a 'high' BMI despite good health. It's a screening tool, not a diagnosis.
Check every 1–3 months if you're actively managing weight, or annually for general health tracking. More frequent checks aren't necessary and can cause unnecessary anxiety.
BMI is calculated the same way, but interpretation differs. Children's BMI is age- and sex-specific; use a paediatrician's growth charts or a child-specific BMI tool for accuracy.
Start with a healthcare provider—they'll assess your overall health, not just BMI. Combine modest calorie reduction, regular physical activity (150 min/week), and stress management; results typically take 8–12 weeks to show.