BMI Calculator
Estimate your Body Mass Index and review broad adult weight-category context
Calculate with BMI Calculator
Your BMI Result
This falls within the adult BMI reference range. BMI is still only one screening measure.
BMI Scale Position
BMI Scale
Ponderal Index (Corpulence Index)
PI = weight / height^3. Normal range: 11-15. Better for very tall or short individuals.
WHO BMI Classification
| Category | BMI Range | Health Risk |
|---|---|---|
| Underweight | < 18.5 | Increased |
| Normal | 18.5 - 24.9 | Low |
| Overweight | 25.0 - 29.9 | Increased |
| Obese Class I | 30.0 - 34.9 | High |
| Obese Class II | 35.0 - 39.9 | Very High |
| Obese Class III | >= 40.0 | Extremely High |
Your result
Method, context, and limits
Use these notes to understand what the estimate is based on, when it helps, and where it can drift.
BMI is weight divided by height squared. It is a screening shortcut, not a direct body-fat measurement.
Use BMI for a fast weight-status check before moving to more specific body-composition or lifestyle decisions.
Very muscular builds, pregnancy, edema, and body-composition differences can make BMI less representative.
Health use guide
Uses the standard adult BMI equation and WHO-style weight-status cutoffs for a quick screening view.
About This Tool
What is Body Mass Index and How Does BMI Calculation Work
Body Mass Index (BMI) is a screening metric that compares weight with height. The formula divides weight in kilograms by height in meters squared (BMI = kg/m2). This calculator supports metric and imperial inputs, then shows the adult BMI category associated with the result. BMI can help frame a conversation about body-size context, but it does not measure body fat directly or distinguish muscle, bone, water, and fat tissue. Treat the result as a broad adult screening estimate, not a diagnosis.
WHO BMI Classification Categories and Weight Context
WHO adult BMI categories provide population-level reference bands, not a diagnosis for an individual person. BMI below 18.5 is classified as underweight, 18.5-24.9 as the reference range, 25.0-29.9 as overweight, and 30 or higher as obesity classes. These labels can help organize follow-up questions, but the same BMI can mean different things depending on muscle mass, age, ethnicity, pregnancy, medical history, and waist circumference. Use your category to decide whether more context is worth reviewing, not as a standalone judgment about health.
BMI Limitations and When to Use Additional Health Metrics
BMI calculations cannot differentiate between lean mass, bone density, water weight, and fat tissue. A muscular person may have a BMI above the reference range without the same body-fat profile implied by the category, while another person may have a reference-range BMI but still need waist, metabolic, or medical context. Age, ethnicity, pregnancy, edema, amputation, and some medical conditions can also affect interpretation. For broader context, compare BMI with waist circumference, waist-to-hip ratio, body fat percentage estimates, and professional assessment when health decisions are involved.
Using BMI Results for Weight Management and Health Goals
Your BMI result is most useful as a starting point for measurement review and planning conversations. If the number is outside the reference range, compare it with waist circumference, body-fat estimate, energy level, training history, and any medical guidance you already have. Use our Calorie Calculator to estimate daily energy needs and our Ideal Weight Calculator to compare formula ranges. Track BMI over time alongside measurements and wellbeing rather than reacting to one reading.
What the Healthy-Weight Range Means
The healthy-weight range shown by the calculator is the weight range that would correspond to the adult BMI reference band for the height entered. It is a mathematical conversion of BMI boundaries, not an individualized goal. Body composition, medical history, age, training status, and clinical guidance may make a different range more appropriate for a specific person.
Common result checks
Questions about this tool
- What does BMI measure?
- BMI compares weight with height using weight in kilograms divided by height in meters squared. It is a broad adult screening estimate and does not directly measure body fat.
- Who is this BMI calculator for?
- The standard adult BMI categories are intended for adults age 18 and older. They may be less useful during pregnancy, for children, and for people whose muscle mass or body composition differs from category assumptions.
- What should I compare with BMI?
- Waist measurement, body fat estimate, health history, activity level, lab results, and professional guidance can add context that BMI alone cannot provide.
- Is this BMI calculator medical guidance?
- No. It provides educational screening context only and should not be used as a diagnosis or treatment plan.