BMI Calculator
About BMI Calculator
Get a precise Body Mass Index assessment tailored to your details. Choose Metric or Imperial units, then enter gender, age, height, and weight to compute BMI instantly and understand your weight category. The tool interprets results in context and can complement BMI with guidance on healthy ranges by age and sex. Use it to monitor progress, screen for underweight or obesity risk, and set actionable goals. Designed for clarity and speed, it works on any device and respects your privacy—calculations are performed locally for fast results without saving your information.
📝 How to Use BMI Calculator
- Select your preferred unit system (Metric or Imperial).
- Enter your weight in kilograms (kg) or pounds (lbs).
- Enter your height in meters (m) or inches (in).
- The calculator will display your BMI and your weight category (Underweight, Normal, Overweight, Obese).
🧮 Formula Used
Metric: BMI = weight (kg) / [height (m)]^2. Imperial: BMI = 703 x weight (lbs) / [height (in)]^2
💡 Example Calculation
- Weight: 70 kg, Height: 1.75 m
- Calculation: 70 / (1.75 * 1.75) = 22.86
- Result: BMI 22.86 (Normal Weight)
❓ Frequently Asked Questions
What is the difference between Standard BMI and New BMI (Oxford)?
Standard BMI (Quetelet Index) assumes weight scales with height squared. The New BMI (Oxford Formula), developed by mathematicians at Oxford University, scales with height^2.5. It is considered more accurate for taller and shorter individuals, preventing 'short' people from thinking they are thinner than they are, and 'tall' people from thinking they are fatter.
How is Body Fat Percentage calculated?
We use the Deurenberg Formula which estimates body fat based on your BMI, Age, and Gender. Generally, women have a higher body fat percentage than men for the same BMI. This provides a more complete picture of your health than BMI alone.
Why do I need to enter my Age and Gender?
While standard BMI only uses height and weight, your Age and Gender are crucial for estimating Body Fat Percentage. As we age, body composition changes, and men and women naturally have different body fat distributions.
Is BMI accurate for athletes or bodybuilders?
No. BMI does not distinguish between muscle and fat. Athletes with high muscle mass may be classified as 'Overweight' or 'Obese' despite having low body fat. In such cases, Body Fat Percentage or waist-to-hip ratio are better indicators.
What is the Ponderal Index?
The Ponderal Index (Corpulence Index) is calculated as weight divided by height cubed. It is often used in pediatrics and for very tall individuals, as it normalizes body mass more effectively across different heights than standard BMI.
How can I reach my Ideal Weight?
Our calculator provides a specific 'Weight to Lose' or 'Weight to Gain' goal to reach the middle of the Normal BMI range (22). Achieving this involves a combination of a balanced, nutrient-rich diet and regular physical activity. Always consult a healthcare provider before starting a weight loss program.