BMI (Body Mass Index) is a measurement of body fat based on height and weight. It's calculated as weight in kg divided by height in metres squared.

What is a healthy BMI range?

For adults, a BMI of 18.5–24.9 is considered normal/healthy. Below 18.5 is underweight, 25–29.9 is overweight, and 30 or above is obese.

Is BMI accurate for everyone?

BMI is a general screening tool but has limitations. It doesn't account for muscle mass, bone density, age, or fat distribution. Athletes may have high BMI due to muscle, not fat.

BMI Calculator - Body Mass Index Calculator

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BMI Calculator

Check your Body Mass Index and healthy weight range

Weight?Your body weight in kilograms. Weigh yourself in the morning without shoes for the most accurate reading.

Height?Your height in centimetres. Example: 5 feet 7 inches = 170 cm.

Weight?Your body weight in pounds.

Height

Age (optional)?Your age in years. Used to show age-adjusted context. BMI interpretation differs slightly for older adults.

yrs

Your BMI

—

UnderNormalOverObese

Healthy Weight Range

—

Weight to Gain/Lose

—

Below 18.5Underweight

18.5 – 24.9Normal weight

25.0 – 29.9Overweight

30.0 and aboveObese

What is BMI?

Body Mass Index (BMI) is a simple numerical measure that uses your height and weight to estimate whether you are at a healthy body weight. It is widely used by doctors and health organisations as a quick screening tool to identify potential weight-related health risks.

While BMI is a useful starting point, it has limitations — it doesn't directly measure body fat or account for muscle mass, age, sex, or ethnicity. A muscular athlete may have a "high" BMI without excess body fat. Always discuss your results with a healthcare professional.

BMI Formula

BMI = Weight (kg) ÷ Height (m)²

Imperial: BMI = 703 × Weight (lb) ÷ Height (in)²

Example: 70kg, 170cm → BMI = 70 ÷ (1.70)² = 24.2

How to use this calculator

Choose Metric (kg/cm) or Imperial (lb/ft/in)
Enter your weight and height accurately
Optionally enter your age for contextual information
Click Calculate BMI to see your result and category
The calculator also shows how much weight to gain or lose to reach the normal range

📘 Example Scenarios

Scenario 1 — Meera checks her BMI 👩

Meera is 165 cm tall and weighs 72 kg. Her BMI = 72 ÷ (1.65)² = 26.4 — slightly overweight. The healthy range for her height is 50–68 kg. She needs to lose approximately 4 kg to reach the upper end of the normal range. This motivates her to make small dietary adjustments.

Scenario 2 — Tom monitors his fitness journey 🏃

Tom is 6 feet tall (183 cm) and weighs 190 lb (86 kg). His BMI = 25.7 — borderline overweight. His healthy range is 125–169 lb. By losing 21 lb (about 10 kg), he'd reach the top of the normal range. He tracks his BMI monthly to monitor progress.

Frequently asked questions

For adults (18+), a BMI between 18.5 and 24.9 is considered healthy. However, for people of Asian descent, some health organisations suggest a lower threshold of 23 for overweight.

Not always. Athletes with high muscle mass can have a BMI in the overweight category despite having very low body fat. Body fat percentage measurement is more accurate for athletes.

For children and teens (2–19 years), BMI is interpreted using age and sex-specific percentile charts, not the adult categories. A paediatrician should interpret children's BMI results.

BMI correlates with health risks at population level but is not a diagnostic tool for individuals. High BMI is associated with increased risk of type 2 diabetes, heart disease, and joint problems. Consult a doctor for a full health assessment.

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