BMI Calculator – Check Your BMI
Estimate your body mass index to see how your current weight compares with common adult BMI ranges.
How this calculator helps
Estimate your body mass index and the weight interval that maps to the standard adult BMI reference range for your height. Choose U.S. customary or metric inputs; switching units converts the values already entered.
Formula: U.S. customary: weight (lb) ÷ height (in)^2 × 703. Metric: weight (kg) ÷ height (m)^2.
Assumptions: This calculator is intended for adults and provides a general screening metric. It does not diagnose health or measure body composition.
Worked example: A 150 lb adult who is 68 in tall has a BMI of (150 ÷ 68²) × 703 ≈ 22.8, which is in the healthy range.
- Inputs: Use your own values for the fields below.
- Adjustments: Recheck your BMI after a meaningful weight change rather than day-to-day fluctuations.
- Output: Use the category as a screening signal, not a diagnosis of health or fitness.
What the result means
The reference weight interval is the set of weights that would produce a BMI from 18.5 to 24.9 at the entered height; it is not an individualized goal or a guarantee of health. BMI is a screening ratio of weight to height, not a direct measure of body fat or health. It can misclassify very muscular people and does not describe body composition.
BMI categories also don't adjust for age, sex, or ethnicity, even though research shows these factors shift what a healthy range looks like for a given individual. A BMI in the "healthy" range doesn't rule out other risk factors, and a BMI slightly outside it doesn't automatically mean poor health.
Because of these limits, BMI is best used as a quick screening number rather than a diagnosis. Pair it with other signals, such as waist circumference, body composition, or a conversation with a healthcare provider, for a fuller picture.
Related calculators
Calorie maintenance, Protein intake, and Steps to distance are closely related to this estimate.
Frequently asked questions
- Is BMI accurate for athletes? Not reliably. Muscle weighs more than fat, so athletes and lifters often score "overweight" despite low body fat.
- Does BMI differ by age? Health risk associated with a given BMI can shift with age, which this simple formula doesn't account for.
- What should I use instead for a fuller picture? Waist circumference, body fat percentage, or a healthcare provider's assessment add context BMI alone can't.
Creator & reviewers
Creator persona
- Quinn ParkerWellness & nutrition estimates
Reviewer personas
- Casey RowanUnits, conversions & measurement
- Sage MitchellClarity & usability review