BMI Calculator
Calculate your Body Mass Index result in seconds with the free BMI Calculator. No registration needed.
Your measurements
Your result
What is a BMI Calculator?
A BMI Calculator estimates your body fat based on your height and weight. It is a quick screening tool that helps determine whether you fall into a healthy weight range. Simply enter your height and weight to get your BMI result instantly.
How to calculate BMI manually (the formula)
BMI = weight (kg) ÷ height (m)². For imperial units, use BMI = (weight in lb × 703) ÷ height (in)². For example, a person weighing 72 kg and 1.75 m tall has a BMI of 72 ÷ (1.75 × 1.75) = 23.5.
Example calculation
A 30-year-old woman who is 165 cm (1.65 m) tall and weighs 62 kg has a BMI of 62 ÷ (1.65 × 1.65) = 22.8. This places her in the healthy weight range.
Common mistakes
- Using the wrong units — mixing kilograms with inches or pounds with meters gives an incorrect result. Always use kg and m (metric) or lb and in (imperial).
- Confusing BMI with body fat percentage — BMI is a screening tool, not a direct measure of body fat. Athletes may have a high BMI but low body fat.
- Ignoring age and gender — BMI does not account for age or gender, which can affect body composition. Use it as a general guide, not a diagnosis.
Frequently asked questions
What is a healthy BMI?
A healthy BMI range is 18.5 to 24.9. Below 18.5 is underweight, 25 to 29.9 is overweight, and 30 or above is obese.
How is BMI calculated?
BMI is calculated by dividing weight in kilograms by height in meters squared (kg/m²). For imperial, multiply weight in pounds by 703 and divide by height in inches squared.
Is BMI accurate for athletes?
BMI may overestimate body fat in athletes because it does not distinguish between muscle and fat.
What is the BMI formula?
The BMI formula is weight (kg) divided by height (m) squared. The result categorizes you as underweight, normal, overweight, or obese.
How do I lower my BMI?
To lower your BMI, aim for a calorie deficit through a balanced diet and regular physical activity. Consult a doctor for a personalized plan.