Free BMI Calculator — Body Mass Index

Calculate your Body Mass Index from height and weight in metric or imperial units. See your BMI category, a visual gauge, and your healthy weight range instantly — free, private, no sign-up.

How to use the BMI Calculator

  1. Enter Height: Go to fixflowhub.com/bmi-calculator and enter your height
  2. Enter Weight: Enter your weight
  3. View Results: See your BMI score and health category instantly

Frequently Asked Questions

How to calculate BMI online?

Go to fixflowhub.com/bmi-calculator, enter your height and weight, and get your BMI calculated instantly with health category. Free, no sign-up.

What is the BMI formula?

Metric: BMI = weight(kg) ÷ height(m)². Imperial: BMI = 703 × weight(lbs) ÷ height(inches)². Both formulas produce the same standardized BMI score regardless of unit system.

What BMI range is considered healthy?

Under 18.5 is underweight, 18.5–24.9 is normal weight, 25–29.9 is overweight, and 30 or above is classified as obese, according to World Health Organization guidelines for adults.

Is BMI accurate for athletes and muscular people?

Not always. BMI does not distinguish between muscle and fat, so muscular individuals can show a high BMI despite having low body fat. Pair BMI with body fat percentage or waist circumference for a fuller picture.

Is BMI calculated the same way for children?

No — children's BMI is interpreted using age- and sex-specific percentile charts rather than the fixed adult ranges, since healthy body composition changes significantly as children grow.

Related free tools

More free calculators