BMI Calculator
Body mass index, or BMI, is one way to understand how your weight relates to your height. It doesn't tell the whole story about your health, but it can provide a useful starting point for understanding weight-related risk and determining what may be worth looking at more closely.
Enter your height and weight below to calculate your BMI.
Your BMI
Enter your height and weight to see your result.
BMI is a screening measure and is not a diagnosis or a substitute for medical advice. It does not account for factors such as muscle mass, body composition, fat distribution, age, genetics, pregnancy, or individual metabolic health. This calculator is intended for adults age 20 and older. It should not be used for children or teens.
What is BMI?
Body mass index is a calculation that compares your weight with your height. Healthcare providers have used it for decades as a simple way to screen for weight categories that may be associated with different levels of health risk.
BMI is useful because it is easy to calculate and provides a consistent reference point. But it is a screening tool, not a comprehensive measure of health.
Two people can have exactly the same BMI and very different body composition, metabolic health, fitness levels, and risk factors.
This is why BMI is most useful when considered alongside additional information rather than interpreted on its own.
How is BMI calculated?
BMI uses the same two measurements you entered above: your weight and your height.
Metric
BMI = weight (kg) ÷ height² (m²)
US
BMI = [weight (lb) ÷ height² (in²)] × 703
The result is expressed as kg/m² and categorized into standard adult BMI ranges.
| BMI | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5–24.9 | Healthy weight |
| 25–29.9 | Overweight |
| 30–34.9 | Class 1 obesity |
| 35–39.9 | Class 2 obesity |
| 40+ | Class 3 obesity |
What does your BMI mean?
Underweight: below 18.5
A BMI below 18.5 falls within the underweight range. In some people this may simply reflect natural body composition, while in others it can be associated with nutritional deficiencies or underlying health issues.
Healthy weight: 18.5–24.9
For most adults, this range is associated with lower weight-related health risk. It does not mean every health marker is automatically optimal.
Overweight: 25–29.9
BMI in this range can be associated with increased health risk, particularly when accompanied by factors such as abdominal fat, high blood pressure, insulin resistance, abnormal cholesterol, or other metabolic markers.
Obesity: 30+
Higher BMI ranges are associated at a population level with increased risk for a number of metabolic and cardiovascular conditions. Individual risk varies considerably, which is why BMI should be interpreted alongside the broader health picture.
What BMI doesn't tell you
A number can be useful. It can also be incomplete.
Muscle vs. body fat
Someone with significant muscle mass can have a higher BMI without having a high level of body fat.
Where body fat is stored
Visceral fat around the abdominal organs can carry different health implications than fat stored elsewhere.
Metabolic health
BMI does not tell you your blood sugar, insulin, cholesterol, blood pressure, inflammatory markers, or other metabolic indicators.
Fitness
Cardiovascular fitness, strength, movement, and physical capacity are not reflected in BMI.
Hormones
Hormonal changes can influence appetite, body composition, metabolism, and weight without being reflected in the BMI calculation.
Genetics and individual biology
Genetics, age, sex, ethnicity, medical history, medications, and other factors can all influence the relationship between BMI and health.
BMI gives us one signal. Better decisions come from understanding the signals around it.
BMI is one piece of metabolic health
Weight alone cannot tell you what is happening beneath the surface.
Someone whose BMI appears to fall within a healthy range can still have insulin resistance, unfavorable cholesterol levels, elevated blood pressure, visceral fat, hormonal changes, or other metabolic risk factors. Likewise, someone with a higher BMI may have stronger metabolic markers than the number alone would suggest.
This is why ANUWELL takes a broader view.
The goal is not simply to categorize weight. It is to understand the biology behind it.
What clinicians may consider alongside BMI:
- BMI
- Waist circumference and body composition
- Blood glucose
- Insulin
- A1C
- Lipids
- Blood pressure
- Hormones
- Medical history
- Sleep
- Activity
- Nutrition
- Medications
- Personal goals
When BMI may matter for weight treatment
BMI is one of several factors healthcare providers may consider when evaluating whether medical weight management is appropriate.
For certain FDA-approved chronic weight-management medications, adult indications generally include obesity, or overweight in the presence of at least one weight-related medical condition. The specific medication, health history, contraindications, current medications, goals, and clinician assessment all matter.
A calculator cannot determine whether treatment is right for you.
Go beyond the number.
ANUWELL helps connect the information that matters, including your goals, health history, labs when appropriate, and physician review, to determine what approach makes sense for you.
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These are prescription treatments. A prescription is issued only if an independent licensed provider determines it is appropriate following review of your health history. Compounded medications are not reviewed or approved by the U.S. Food and Drug Administration. Full medical and prescribing disclosures are available in the site footer.
More tools to understand your numbers
BMI can be useful as a screening measure, but it does not directly measure body fat, body composition, metabolic health, or fitness. It is best considered alongside other health information.
For adults age 20 and older, a BMI from 18.5 to below 25 falls within the healthy weight category.
Standard adult BMI calculations use the same height-and-weight formula regardless of sex, although BMI does not account for differences in body composition.
No. BMI may be one factor used by healthcare providers when assessing treatment options, but medication eligibility and appropriateness depend on additional clinical information and evaluation by a licensed healthcare provider.
BMI questions, answered
BMI questions, answeredFAQ — 04
See all FAQs →Your BMI is a starting point. Not the whole picture.
Understanding your health means looking beyond a single number. ANUWELL combines physician-guided care with the information needed to make more informed decisions about weight, metabolic health, hormones, longevity, and treatment.
References
- Centers for Disease Control and Prevention. Adult BMI Categories. cdc.gov/bmi/adult-calculator/bmi-categories.html
- Centers for Disease Control and Prevention. Adult BMI Calculator. cdc.gov/bmi/adult-calculator
- U.S. Food and Drug Administration. Prescribing information for FDA-approved chronic weight-management medications. accessdata.fda.gov