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BMI FAQ: Answers to the Most Common Questions

Clear answers to the most common BMI questions — what the number means, how it's calculated, and how the calculator works.

Published August 28, 20264 min read
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BMI Calculator: frequently asked questions

Straight answers to the questions people ask most about BMI and the BMI Calculator.

What does my BMI number mean?

The calculator sorts your BMI into standard WHO categories: under 18.5 is underweight, 18.5–24.9 is normal, 25–29.9 is overweight, and 30 and above is obese. These ranges are a screening guide, not a diagnosis.

How is BMI calculated?

BMI is your weight in kilograms divided by the square of your height in meters — BMI = weight (kg) / height (m)^2. The calculator does this for you, including unit conversion if you enter imperial values.

Does BMI work the same for men and women?

Yes. The formula and categories are the same regardless of sex. BMI is a rough population-level measure and does not distinguish muscle from fat.

Do I need to install or enter anything besides height and weight?

No installation and no account. Just type your height and weight, pick metric or imperial, and press Calculate.

Verdict

If you need a quick, reliable body mass index, the BMI Calculator does it in seconds with just two inputs.

Free tools to do it now

Frequently asked questions

What is a healthy BMI?

A BMI between 18.5 and 24.9 is considered a normal, healthy range for most adults.

How does the BMI Calculator determine category?

It compares your computed BMI to the WHO ranges for underweight, normal, overweight, and obese.

Can BMI be wrong for athletes?

Yes — it does not account for muscle mass, so very muscular people can show a high BMI with low body fat.

What units can I enter?

Both metric (kg and m) and imperial (lbs and ft/in) are supported, with automatic conversion.

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