What this estimate does not cover
- Pick your unit system. Everything below switches with it.
- Enter your age, weight and height. The result updates as you type.
- Read the category the CDC assigns to your BMI.
- Copy the link if you want to keep or share this exact result.
The ranges shown next to each field come from the calculator's own validation. The lower age bound of 20 is CDC's: they direct children and teens aged 2–19 to a separate calculator, because BMI categories are not built for them.
BMI is weight divided by height squared. It is one number derived from two measurements, and that is both its usefulness and its limit: it cannot tell which part of you is heavier.
| BMI | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 to below 25 | Healthy Weight |
| 25 to below 30 | Overweight |
| 30 to below 35 | Class 1 Obesity |
| 35 to below 40 | Class 2 Obesity |
| 40 or greater | Class 3 Obesity (Severe Obesity) |
It cannot distinguish fat from muscle. This is the single biggest limitation. A person who trains and carries more muscle will score higher than a sedentary person of the same weight and height, without being any less healthy for it.
The CDC states plainly that BMI is a screening measure, not a diagnostic one. It is designed to flag who should be assessed further — not to tell an individual what their health is.
The categories are also not adjusted for age, sex or race, and are not validated for all populations. Athletes, pregnancy, and many ethnic groups are all known cases where the categories mislead.
Why is there no sex field?
Because the equation does not use one. The CDC publishes these categories as a flat rule for adults 20 and older, based on BMI "regardless of age, sex, or race". A calculator that asked for your sex here would imply the result changes with it, and it does not.
Why is the minimum age 20?
CDC states its categories are for adults 20 and older, and directs children and teens aged 2–19 to a separate, age-specific calculator. BMI percentageiles for young people work completely differently, and using adult cut-offs on a child would give a meaningless result.
Is there really no maximum age?
CDC publishes no upper age bound — the rule is stated as applying to everyone aged 20 and older. The limit of 120 on this page is a plausibility bound we set on ourselves, not a limit from the source, and we say so rather than attributing it to the CDC.
Does it change if I enter pounds and inches?
Almost. Metric inputs use the exact formula above. Imperial inputs use the historical constant 703, which is the form CDC's printed tables used for decades. The current CDC pages do not publish that constant, so we flag it as a project constant rather than a verified current source figure. If the two routes disagree slightly for the same person, this is why.
My BMI is high but I am not overweight. Why?
Quite possibly. Because BMI only sees weight and height, a high muscle mass reads the same as a high fat mass. This is precisely why CDC calls it a screening measure. If your result concerns you, take it to a clinician who can measure body composition properly.
Should I use this while pregnant?
No. The CDC categories are not designed for pregnancy, where weight gain is expected and BMI is not interpretable. Speak to a doctor or midwife.
Centers for Disease Control and Prevention. Adult BMI Categories. CDC, updated 19 March 2024. cdc.gov/bmi/adult-calculator
Population covered: adults aged 20 and older, per CDC. CDC publishes no upper age bound, so the limit of 120 shown on this page is a project plausibility bound and not a source limit. The imperial constant 703 is a project constant historically associated with CDC's printed tables; it is not published on the current CDC page.