BMI Calculator
Quick answer
Enter your height, weight, age and activity level to instantly get your Body Mass Index (BMI), the WHO category it falls into, your healthy weight range and an estimate of your daily calorie needs. BMI is weight in kilograms divided by height in metres squared (kg/m²).
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Your details
Used to calculate BMI, ideal weight and daily calories.
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The BMI formula
BMI = weight (kg) ÷ height (m)²
Imperial: BMI = 703 × weight (lb) ÷ height (in)²
We also estimate your Basal Metabolic Rate with the Mifflin-St Jeor equation and multiply it by an activity factor (1.2–1.9) for daily calories.
Worked example
- 1
A woman weighs 68 kg and is 165 cm tall (1.65 m).
- 2
Height squared: 1.65 × 1.65 = 2.7225.
- 3
BMI = 68 ÷ 2.7225 = 25.0 — the edge of the “normal” range.
- 4
Her healthy weight range is 18.5–24.9 × 2.7225 ≈ 50.4–67.8 kg.
Interpreting your BMI
| Your result | Category | What it means |
|---|---|---|
| Below 18.5 | Underweight | Below the healthy band for most adults. Gradual, purposeful weight gain with whole foods and strength training works best under professional guidance. |
| 18.5 – 24.9 | Normal weight | Within the healthy range for most adults. Sustain it with balanced nutrition, regular movement and good sleep. |
| 25.0 – 29.9 | Overweight | Slightly above the healthy range. Consistent habits — daily walks, strength work, mindful portions — shift the trend. |
| 30.0 or above | Obese | Above the healthy range. A healthcare provider can help you set safe, sustainable and personal goals. |
World Health Organization (WHO) categories for adults aged 20 and over.
Frequently asked questions
Sources & further reading
No History Yet
Your BMI tracking history will appear here. Start by calculating your BMI above to see your progress over time.
The four BMI categories, explained simply
BMI is a quick screening tool. It doesn't measure body fat directly, but it is a useful starting point to understand where you sit.
Below the healthy range
Often linked to under-eating, high stress, illness or very high training volume. Sustainable weight gain focuses on calorie-dense food and strength training.
Your BMI is below the healthy range. Consider speaking with a healthcare provider about safe, sustainable weight gain strategies.
Inside the healthy range
Associated with the lowest cardiometabolic risk for most adults. The goal here is consistency — keep moving, eating well and sleeping enough.
Great — you are within the healthy BMI range. Keep up your balanced lifestyle, regular movement and good sleep.
Slightly above healthy
A common range that responds extremely well to small habit changes — daily walks, more protein and fewer ultra-processed foods.
Your BMI is slightly above the healthy range. Small, steady habits — daily walks, strength training and balanced meals — can make a big difference.
Higher cardiometabolic risk
Associated with increased risk for type 2 diabetes, heart disease and joint issues. A 5–10% weight reduction can make a major difference.
Your BMI is in the obese range. Consider consulting a healthcare provider for personalized guidance on nutrition, activity and long-term health.
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