Free BMI Calculator Online
Calculate your Body Mass Index instantly. Know your healthy weight range, ideal BMI, and personalized health tips — free!
<18.5 Normal
18.5–24.9 Overweight
25–29.9 Obese I
30–34.9 Obese II
>35
| Category | BMI Range | Health Risk |
|---|---|---|
| Underweight | < 18.5 | Malnutrition risk |
| Normal Weight | 18.5 – 24.9 | Low risk (healthy) |
| Overweight | 25.0 – 29.9 | Moderate risk |
| Obese Class I | 30.0 – 34.9 | High risk |
| Obese Class II+ | > 35.0 | Very high risk |
📖 What is BMI?
Body Mass Index (BMI) is a measure that uses your height and weight to estimate whether you are underweight, normal weight, overweight, or obese.
BMI is calculated as: weight (kg) ÷ height² (m²). For example, if you weigh 70 kg and are 1.75 m tall, your BMI = 70 ÷ (1.75 × 1.75) = 22.9 (Normal).
It is used by doctors, nutritionists, gyms, and health insurance companies worldwide as a quick health screening tool.
🚀 How to Use
- Choose your preferred unit — Metric (kg/cm) or Imperial (lb/ft).
- Select your gender (Male or Female).
- Enter your weight, height and age.
- Click “Calculate My BMI” for instant results.
- View your BMI score, category, ideal weight range & health advice.
⭐ Features of Our BMI Calculator
- Supports Metric (kg/cm) & Imperial (lb/ft/in)
- Animated BMI gauge with visual indicator
- WHO-standard BMI classification
- Ideal healthy weight range calculation
- BMI Prime score (ratio to upper normal limit)
- Gender-aware results & tips
- Instant results — no button lag
- 100% free — no login required
- No data stored — 100% private
- Mobile, tablet & desktop friendly
According to the World Health Organization (WHO), a BMI between 18.5 and 24.9 is considered a healthy or normal weight range for adults. A BMI below 18.5 indicates underweight, while 25–29.9 is overweight and 30 or above is classified as obese.
BMI is a useful screening tool but has limitations. It does not distinguish between muscle and fat — so a muscular athlete may have a “high” BMI but still be very healthy. It also may not accurately reflect health for children, elderly people, pregnant women, or certain ethnicities. Always consult a doctor for a complete health assessment.
Ideal weight is the weight range that corresponds to a healthy BMI (18.5–24.9) for your specific height. For example, if you are 170 cm tall, your ideal weight range is approximately 53.5 kg to 72.0 kg. Our tool calculates this range automatically based on the height you enter.
BMI Prime is the ratio of your BMI to the upper limit of the normal BMI range (25). A BMI Prime of 1.0 means your BMI is exactly at the normal/overweight boundary. Values below 1.0 are in the normal or underweight range; values above 1.0 indicate overweight or obesity. It gives a simple, intuitive way to understand your BMI relative to the healthy limit.
The BMI formula is the same for men and women, but the health implications can differ. Women naturally carry more body fat than men at the same BMI due to biological differences. Some health organizations suggest slightly different BMI interpretations for women, though the WHO standard ranges (18.5–24.9 = normal) apply to both genders in general clinical use.