Calculate your Body Mass Index instantly and discover your healthy weight range. Understand your BMI category and get personalized recommendations for your health journey.
Body Mass Index (BMI) is a screening measure that compares an adult's weight with the square of their height. Calculate it with BMI = weight in kilograms ÷ height in metres², or BMI = 703 × weight in pounds ÷ height in inches². For most adults, standard categories are underweight below 18.5, healthy weight from 18.5 to 24.9, overweight from 25.0 to 29.9, and obesity at 30.0 or above. BMI is useful for identifying population-level weight patterns, but it is not a diagnosis and does not directly measure body fat. Muscle mass, age, ethnicity, pregnancy, and fat distribution can affect how an individual result should be interpreted. Use your BMI as a starting point alongside measures such as waist circumference, body composition, medical history, and advice from a qualified healthcare professional. Different assessment methods apply to children and teenagers.
Worked example: For an adult who weighs 70 kg and is 1.70 m tall, BMI = 70 ÷ (1.70 × 1.70) = 24.2. This result falls within the standard healthy-weight range of 18.5–24.9.
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Practical steps toward a healthy weight.
BMI doesn't distinguish fat from muscle. Two people can have the same BMI with very different health profiles. Pair your BMI score with body fat percentage and waist circumference for the full picture.
A 300–500 kcal daily deficit leads to 0.3–0.5 kg of fat loss per week — sustainable and muscle-preserving. Crash diets cause muscle loss and metabolic slowdown, making long-term BMI improvement harder.
Resistance training builds muscle (which may raise BMI slightly) while dramatically improving metabolic health, body composition, and the risk factors that BMI attempts to predict.
Treat BMI as a screening signal, not a verdict on your health. Two people with the same BMI can have very different body composition: a strength athlete may sit in the overweight range because of muscle, while someone with a normal BMI can still carry excess visceral fat. Age, ethnicity, pregnancy, and medical history all change how a number should be read.
Pair your result with waist circumference or waist-to-height ratio, body-fat estimates, fitness markers, and clinical advice. If your BMI is outside the healthy range — or you have symptoms, a chronic condition, or are under 18 — use this result for education and planning only, and talk with a qualified healthcare professional before making major diet or training changes.
Your BMI questions answered.
A BMI of 18.5–24.9 is considered normal/healthy for most adults. Under 18.5 is underweight, 25–29.9 is overweight, and 30+ is classified as obese. Different thresholds apply for certain Asian populations.
BMI is a useful screening tool but has limitations. It doesn't account for muscle mass, age, sex, or fat distribution. A muscular athlete can have an "overweight" BMI. Always interpret BMI alongside other health markers.
BMI = weight (kg) ÷ height² (m²). For imperial units: BMI = 703 × weight (lbs) ÷ height² (inches²). The definition section above walks through a full worked example with categories.
Reduce caloric intake by 300–500 kcal/day below your TDEE, increase physical activity (especially cardio and resistance training), improve sleep quality, and manage stress. Target 0.5 kg/week of fat loss for sustainable BMI improvement.
The healthy BMI range of 18.5–24.9 translates to: a 160 cm person should weigh 47–64 kg; a 170 cm person should weigh 53–72 kg; a 180 cm person should weigh 60–81 kg. Your calculator shows your specific range.
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Browse All Tools →Adult BMI categories and the weight-for-height formula used on this page follow widely cited public-health guidance:
This calculator gives a general estimate for education and planning. It is not a medical diagnosis and does not replace advice from a qualified healthcare professional. Talk to your doctor before acting on these results — especially if you are pregnant, under 18, or managing an existing medical condition.