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BMI Calculator

Enter your height and weight to calculate your Body Mass Index and see which standard category it falls into.

Your BMI

BMI is a general screening measure, not a diagnosis. It doesn't account for muscle mass, bone density, or body composition. Consult a healthcare provider for personalized health assessment.

How to use the BMI Calculator

  1. Choose metric or imperial units.
  2. Enter your height and weight in the selected units.
  3. Your BMI value and category (underweight, normal, overweight, obese) appear instantly.
  4. Switch units at any time to double-check your entry.

About the BMI Calculator

Body Mass Index (BMI) is a simple screening calculation that relates a person's weight to their height, producing a single number used as a general population-level indicator of whether someone falls within a typical weight range. It's calculated as weight in kilograms divided by height in meters squared, and is the same formula used by health organizations worldwide, including the World Health Organization, for population health screening and research.

This calculator accepts either metric (centimeters and kilograms) or imperial (feet, inches, and pounds) input, converting internally so the result is identical regardless of which unit system you use. Once calculated, the result is placed into one of the four standard WHO categories: underweight (below 18.5), normal weight (18.5–24.9), overweight (25–29.9), or obese (30 and above) — the same thresholds used in most standard medical references.

BMI is useful as a quick, standardized reference point, but it has well-documented limitations: it doesn't distinguish between muscle and fat mass, so a very muscular person can show a higher BMI without carrying excess fat, and it doesn't account for factors like bone density, age, sex, or where fat is distributed on the body, all of which matter for actual health risk assessment. For that reason, this tool (like BMI generally) is best used as a general screening reference point rather than a diagnostic tool — a conversation with a healthcare provider is the right next step for a personalized assessment.

Frequently asked questions

Is BMI an accurate measure of health for everyone?+
No. BMI is a population-level screening tool and doesn't account for muscle mass, bone density, age, sex, or fat distribution, so it can be misleading for athletes, older adults, or anyone with an atypical body composition. It's a starting reference point, not a diagnosis.
What are the standard BMI categories?+
Underweight is below 18.5, normal weight is 18.5–24.9, overweight is 25–29.9, and obese is 30 and above — these are the widely used World Health Organization reference ranges for adults.
Does this calculator work for children?+
No, BMI interpretation for children and teens uses age- and sex-specific percentile charts rather than the fixed adult categories used here. This calculator is designed for adult BMI calculation.
Should I make health decisions based on this number alone?+
No, BMI is best used as one general reference point among many. For any health or weight-related decisions, it's best to consult a doctor or qualified healthcare provider who can consider your full health picture.

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