BMI Calculator
Calculate your Body Mass Index. Supports metric (cm/kg) and imperial (ft/in/lbs). All local, no data stored.
About this tool
The BMI Calculator computes your Body Mass Index using standard formulas, with support for both metric (centimeters and kilograms) and imperial (feet, inches, and pounds) units. BMI is a widely used screening tool that estimates whether your weight is in a healthy range for your height.
The tool displays your BMI number, classification category (Underweight, Normal weight, Overweight, or Obese), and a visual scale showing where your result falls. All calculations happen instantly in your browser — no data is stored or sent anywhere.
BMI is a useful population-level health indicator, but it has limitations. It does not distinguish between muscle and fat, and it does not account for body composition, age, sex, or ethnicity. Use this as a general guideline, not a medical diagnosis.
How to use
- Select unit system. Choose Metric (cm / kg) or Imperial (ft/in / lbs) using the toggle buttons.
- Enter your measurements. Input your height and weight. The calculator updates instantly as you type — no need to click a button.
- Read your result. Your BMI number appears along with a category (Underweight <18.5, Normal 18.5–24.9, Overweight 25–29.9, Obese 30+) and a visual marker on the color-coded scale.
Frequently asked questions
Is my height and weight data stored?
No. All calculations happen in your browser using JavaScript. Your measurements never leave your device. Nothing is stored, logged, or transmitted to any server.
Is BMI accurate for everyone?
BMI has known limitations. It does not distinguish between muscle and fat — athletes with high muscle mass may be classified as overweight or obese despite being healthy. It also does not account for age, sex, ethnicity, or body fat distribution. BMI is best used as a general screening tool, not a definitive health assessment. Consult a healthcare professional for personalized advice.
How is BMI calculated?
Metric: BMI = weight (kg) / height (m)². For example, 70 kg / (1.75 m)² = 22.9.
Imperial: BMI = (weight (lbs) / height (in)²) × 703. For example, (154 lbs / 69²) × 703 = 22.8.
Does this work on mobile?
Yes. The BMI Calculator is fully responsive and works on all modern browsers including iOS Safari and Android Chrome.