# BMI Calculator — Free, Metric & Imperial

Calculate your Body Mass Index from weight and height, in metric or imperial. 100% in your browser — free, no sign-up.

## What is BMI?

Body Mass Index (BMI) is a number calculated from your weight and height that gives a general indication of whether you are underweight, a normal weight, overweight, or obese. It is a quick screening guide used widely in health contexts.

## How it works

Enter your weight and height in metric (kg, cm) or imperial (lb, in). BMI is computed in your browser using the standard formula and matched to the standard category ranges. Nothing is sent anywhere.

## BMI categories

The usual ranges are: under 18.5 underweight, 18.5–24.9 normal weight, 25–29.9 overweight, and 30 or above obese. They apply to adults and are a general guide, not a personal diagnosis.

## Limits of BMI

BMI does not distinguish muscle from fat or account for age, sex, or body composition, so very muscular people can read as overweight. Treat it as a starting point and consult a professional for a real assessment.

## How to

1. Pick metric or imperial units.
2. Enter your weight and height.
3. Read your BMI and category.

## FAQ

**Which units can I use?**

Both metric (kg, cm) and imperial (lb, in). Switch units and the formula adjusts automatically.

**What are the BMI categories?**

Under 18.5 underweight, 18.5–24.9 normal, 25–29.9 overweight, 30+ obese. These apply to adults as a general guide.

**Is BMI accurate for everyone?**

No. BMI does not separate muscle from fat or account for age, sex, or build, so it is a screening guide, not a diagnosis.

**Is my data private?**

Yes. BMI is calculated in your browser; nothing is sent anywhere.

**Is it free?**

Yes, completely free — no sign-up and no watermark.


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