Your age does not change the BMI formula. It changes the additional model comparison. Muscle mass, weight history and medical context remain relevant, even when a result lies within the middle SBMI band.
BMI reference ranges in the SBMI model
On small screens, scroll the table sideways.
| Age group | Example age | SBMI 20–30 | SBMI 30–40 | SBMI 40–50 |
|---|---|---|---|---|
| 20–29 | 25 | 18.3–<19.4 | 19.4–<26.0 | 26.0–<30.8 |
| 30–39 | 35 | 18.4–<19.6 | 19.6–<26.5 | 26.5–<33.0 |
| 40–49 | 45 | 18.6–<19.8 | 19.8–<27.1 | 27.1–<34.4 |
| 50–59 | 55 | 18.8–<20.1 | 20.1–<27.7 | 27.7–<35.5 |
| 60–69 | 65 | 19.1–<20.5 | 20.5–<28.5 | 28.5–<36.6 |
| 70–79 | 75 | 19.4–<20.9 | 20.9–<29.3 | 29.3–<37.8 |
| 80–89 | 85 | 19.8–<21.4 | 21.4–<30.2 | 30.2–<39.1 |
| 90–95 | 95 | 20.3–<21.9 | 21.9–<31.2 | 31.2–<40.5 |
How to read these tables
SBMI is this website’s age- and sex-dependent model. These tables describe model positions, not diagnoses, personal risk estimates or clinical treatment targets. They use the original reference data without the optional ancestry adjustment and cover adults only. The rounded 30–39 score band in the calculator is not an exact cut-off at the reference curves.
How BMI differs from SBMI
BMI is weight in kilograms divided by height in metres squared. Standard adult BMI categories do not change with age or sex. SBMI adds an age- and sex-dependent interpretation; its reference bands must not be confused with standard BMI categories.
Example: at 70 kg and 1.75 m, BMI = 70 ÷ (1.75 × 1.75) = 22.9. Age and sex do not alter this BMI number; they affect the additional SBMI interpretation.