BMI Calculator
The BMI Calculator estimates your Body Mass Index from your height and weight, a widely used general screening measure for weight categories. Because BMI divides weight by height squared, the formula tends to overestimate body fat in taller people and underestimate it in shorter people — a mathematical artifact noted since the metric (originally Adolphe Quetelet's 1830s "Quetelet Index") was designed for population statistics, not individual diagnosis. Some health bodies also apply lower BMI thresholds for people of Asian descent (roughly 23 for overweight, 27.5 for obesity) because research has linked elevated health risk to lower BMI values in these populations. The standard 18.5–30 cutoffs used here are also the same for everyone regardless of age or sex, even though body fat naturally rises with age at an identical BMI.
Switch between U.S. Customary and Metric units.
How This Tool Works
Switch between U.S. and Metric units with the toggle, enter your height and weight, and get your BMI along with its standard weight category.
Formula & Method
BMI = weight (kg) ÷ height (m)². Categories: under 18.5 (underweight), 18.5–24.9 (healthy), 25–29.9 (overweight), 30+ (obesity).
Example Calculation
Say someone is 5'6" tall and weighs 150 lb. First convert to metric: height = (5×12 + 6) inches = 66 inches × 0.0254 = 1.6764 m; weight = 150 lb × 0.453592 = 68.04 kg. Square the height: 1.6764 m × 1.6764 m = 2.8103 m². Divide weight by height squared: 68.04 ÷ 2.8103 = 24.2. A BMI of 24.2 falls in the 18.5–24.9 range, so the calculator reports a "Healthy weight" category.
Frequently Asked Questions
What is a healthy BMI?+
A BMI between 18.5 and 24.9 is generally classified as a healthy weight range for most adults, though it doesn't account for muscle mass or body composition.
Is BMI accurate for athletes?+
Not always — muscular individuals often show a higher BMI despite having low body fat, since BMI doesn't distinguish between muscle and fat mass.
Should I make health decisions based on BMI alone?+
No, talk to a healthcare provider — BMI is a general screening tool, not a diagnostic measure, and other factors like waist circumference and body composition matter too.
Does BMI use different formulas for men and women?+
No — this calculator applies the exact same BMI formula (weight in kg ÷ height in m²) regardless of sex, since the standard BMI weight categories aren't sex-specific. Tools like the Body Fat Calculator's U.S. Navy method, by contrast, do factor in sex-based differences in fat distribution.
Can BMI be misleading at very short or very tall heights?+
Yes. Because the formula divides weight by height squared, the same body proportions produce a higher BMI in taller people and a lower BMI in shorter people, purely as a mathematical side effect rather than an actual difference in body fat. This is one reason BMI works best as a population-level screening tool rather than a precise individual measure.
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<a href="https://everyfix.net/tools/bmi-calculator/">BMI Calculator</a> by <a href="https://everyfix.net">EveryFix</a>Related Tools
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