Dr. Benjamin H. Krasne, M.D.
Board-certified physicianBoard-certified in anesthesiology, he reads medications and metabolism with a pharmacologist's eye, which shapes how he doses weight loss and longevity care.
Check your BMI in seconds
BMI calculator for adults and GLP-1 eligibility
Enter your height and weight to see your body mass index and CDC weight category. Then see whether you may meet the BMI thresholds clinicians use when considering GLP-1 weight loss medication.
- Free, no account or email
- CDC adult weight categories
- See GLP-1 BMI thresholds
Free to book. You pay only if you go ahead with treatment.
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Licensed U.S. clinician review
Time: Under a minute
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5–10 minphone or video
No insuranceneeded
LicensedU.S. clinicians
0.0Enter your height and weight
Your result updates as you type. BMI is a screening number, not a diagnosis.
Why use the BMI calculator from My IV Doctors
Instant, private result
Enter your height and weight in U.S. or metric units and get your BMI right away. Nothing you type is saved, and no sign-up is needed.
Categories you can trust
Your number is matched to the CDC's adult categories, including the three obesity classes, so you know exactly where you stand.
Clear GLP-1 context
See whether your BMI reaches the thresholds clinicians use when considering weight loss medication, explained in plain language without jargon.
A free next step
If your result raises questions, book a free 5–10 minute phone or video consultation with a licensed U.S. clinician to talk through your options.
How to use the BMI calculator
- 1
Enter your height and weight
Use feet, inches and pounds, or switch to centimeters and kilograms. Your result appears right away.
- 2
See your BMI category
The calculator places your BMI in one of the CDC adult categories, from underweight to class 3 obesity.
- 3
Check GLP-1 BMI thresholds
If your BMI is 30 or higher, or 27 or higher with a weight-related health condition, you may be a candidate for prescription weight loss medication.
- 4
Pick a time for your free visit
A licensed clinician reviews your history, medications and goals in a 5–10 minute phone or video visit and decides whether treatment is appropriate.
Who this BMI calculator is for
Adults 20 and older
The CDC's adult categories apply from age 20. The results on this page are meant for adults only.
People considering GLP-1 medication
If you're curious whether you may be a candidate for semaglutide, tirzepatide or a similar medication, your BMI is one of the first things a clinician looks at.
Adults tracking weight over time
Checking your BMI every few months can show a trend over time, especially alongside other measures like waist size.
Not for children and teens
People under 20 are assessed with BMI-for-age percentiles on growth charts, because healthy body composition changes as children grow.
Not for use during pregnancy
BMI categories don't apply during pregnancy. Weight loss medications aren't used in pregnancy, so talk with your prenatal provider instead.
BMI ranges and GLP-1 medication eligibility
| BMI range | CDC category | GLP-1 medication |
|---|---|---|
| Below 18.5 | Underweight | — |
| 18.5 to under 25 | Healthy weight | — |
| 25 to under 27 | Overweight | Below the usual threshold |
| 27 to under 30 | Overweight | May be an option with a weight-related condition |
| 30 or higher | Obesity (class 1, 2 or 3) | May be an option |
What is BMI?
Body mass index compares your weight with your height. The formula is your weight in kilograms divided by the square of your height in meters, or, in U.S. units, your weight in pounds divided by your height in inches squared, multiplied by 703. The calculator on this page does the math for you, and nothing you type is stored.
The CDC describes BMI as a quick, inexpensive screening measure. It's moderately to strongly linked with measures of body fat, which is why clinicians use it as a starting point. It doesn't measure fat directly, though, and it can't tell muscle from fat or show where your body carries weight. That's why a BMI result is a reason for a conversation, not a diagnosis.
For weight loss care, BMI also matters for a practical reason: the FDA-approved uses of prescription weight-management medications, including GLP-1 medicines, are built around BMI thresholds. Knowing your number helps you understand whether a consultation about medication makes sense.
Adult BMI categories from the CDC
These are the CDC's categories for adults 20 and older. The obesity range is split into three classes because health risks tend to rise as BMI climbs.
- Underweight: below 18.5
- Healthy weight: 18.5 to under 25
- Overweight: 25 to under 30
- Class 1 obesity: 30 to under 35
- Class 2 obesity: 35 to under 40
- Class 3 (severe) obesity: 40 or higher
BMI requirements for GLP-1 medication
According to the National Institute of Diabetes and Digestive and Kidney Diseases, prescription weight-management medication may be an option for adults with a BMI of 30 or higher, or a BMI of 27 or higher who also have a weight-related health problem. Common examples of those conditions are high blood pressure, type 2 diabetes, high cholesterol and obstructive sleep apnea.
Meeting a threshold doesn't mean a prescription is automatic. A clinician also considers your medical history, current medications, past weight loss attempts and any conditions that rule out certain drugs, such as medullary thyroid cancer (yours or a family member's) for GLP-1 medicines. Brand-name medications like Wegovy and Zepbound are trademarks of their manufacturers and may cost extra. Compounded semaglutide and tirzepatide are prepared by licensed U.S. compounding pharmacies and are not FDA-approved.
BMI limitations: muscle, age and body fat
Because BMI only uses height and weight, it can misread some bodies. Very muscular people may land in the overweight range with little body fat, while older adults who have lost muscle can carry more fat than their BMI suggests. Two people with the same number can have very different metabolic health.
That's why clinicians pair BMI with other information: waist circumference, blood pressure, lab work such as blood sugar and cholesterol, and your personal and family history. If your BMI sits near a threshold, those details often matter more than a fraction of a point.
BMI calculator limitations and safety
A calculator can't examine you. Treat your BMI as one piece of information and talk with a clinician before making major changes to how you eat, exercise or take medication.
- A BMI below 18.5 can signal a health problem; weight loss treatment isn't appropriate, and it's worth seeing a clinician
- Don't start, stop or change prescription medication based on a BMI result alone
- GLP-1 medications aren't for use during pregnancy, and some people with certain thyroid or pancreatic histories shouldn't take them
- If you have, or have had, an eating disorder, focus on care with your own clinician rather than BMI targets
- Sudden, unexplained weight loss or gain deserves a medical check whatever your BMI
Physicians who oversee your care
Independently licensed U.S. physicians supervise every treatment we offer.
Dr. Johnathan Chance Miller, M.D.
PhysicianTrained at Columbia and Washington University, he pairs prescriptions with practical habits around food, training and sleep.
Dr. Vanessa Niles, R.N., M.D., F.A.C.O.G.
OB-GYN, board certifiedAn OB-GYN for more than 40 years and a Fellow of ACOG, she leads women's health care, from perimenopause to PCOS.
BMI questions, answered
Still deciding? The first consultation is free and takes about 5–10 minutes.
Book a free consultationHow do I calculate BMI by hand?
Divide your weight in kilograms by your height in meters squared. In U.S. units, divide your weight in pounds by your height in inches squared and multiply by 703. For example, 200 pounds at 5 feet 10 inches (70 inches) gives a BMI of about 28.7.
What is a normal BMI for adults?
The CDC calls a BMI of 18.5 to under 25 a healthy weight for adults. From 25 to under 30 is overweight, and 30 or higher is obesity.
What BMI do you need for a GLP-1 prescription?
Clinicians usually look for a BMI of 30 or higher, or 27 or higher if you also have a weight-related condition like high blood pressure or type 2 diabetes. Those thresholds match the FDA-approved uses of weight-management medications, and a clinician still has to decide treatment is right for you.
What counts as a weight-related health condition?
Common examples are high blood pressure, type 2 diabetes or prediabetes, high cholesterol and obstructive sleep apnea. Your clinician will consider your full history during the consultation.
Can I get weight loss medication with a BMI of 26?
Usually not. Prescription weight loss medications are generally reserved for a BMI of 27 or more with a related condition, or 30 or more. A clinician can still talk with you about other ways to manage your weight.
Is BMI accurate for athletes?
Not always. BMI can't distinguish muscle from fat, so very muscular people may score in the overweight or obesity range without excess body fat. Waist size and other measures give a fuller picture.
Is BMI accurate for older adults?
The same categories are used, but older adults often lose muscle, so BMI can underestimate body fat. Clinicians look at other factors alongside it.
Can I use an adult BMI calculator for my child?
No. For anyone under 20, BMI is interpreted with age- and sex-specific percentiles on CDC growth charts. Your child's pediatrician can do this for you.
What does class 3 obesity mean?
Class 3, sometimes called severe obesity, is a BMI of 40 or higher. It's linked with higher health risks, and treatment options can include medication, along with other approaches your clinician may discuss.
Does this BMI calculator save my information?
No. The calculator runs in your browser and doesn't store or send the height and weight you enter.
Is waist size a better measure than BMI?
They measure different things. Waist size reflects fat around the abdomen, which is linked with metabolic risk, so clinicians often use both together.
How often is it worth rechecking my BMI?
Every few months is enough for most adults. If you're on a weight loss program, your clinician will track your progress at follow-up visits.
What happens during a free weight loss consultation?
You talk with a licensed clinician for 5–10 minutes by phone or video. They review your BMI, health history and medications, and if treatment is appropriate, they explain your options and costs. There's no obligation and no insurance needed.
Know your BMI, then talk with a clinician for free
The BMI calculator is free and takes under a minute. If you want to explore weight loss medication, book a free 5–10 minute phone or video consultation next.
Related services
References
- CDC: Adult BMI categories
- CDC: About body mass index (BMI)
- NIDDK (NIH): Prescription medications to treat overweight and obesity
Medically reviewed October 2026. This page is general information and not a substitute for advice from your own clinician. Read our editorial policy.
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