The standard BMI ranges
| Category | BMI range |
|---|---|
| Underweight | Below 18.5 |
| Healthy weight | 18.5 – 24.9 |
| Overweight | 25.0 – 29.9 |
| Obese range | 30.0 and above |
BMI (Body Mass Index) is calculated from just two numbers — height and weight — using the formula weight (kg) ÷ height (m)². It was designed in the 1830s as a population-level statistical tool, not an individual diagnostic test, which explains a lot about its limitations.
Get your BMI and healthy weight range instantly:
Open the BMI CalculatorWhy BMI isn't the full story
- It can't tell muscle from fat. A very muscular person can land in the "overweight" range while having low body fat — muscle is denser than fat, so it weighs more for the same volume.
- It ignores where fat is stored. Fat around the waist and organs carries more health risk than fat elsewhere, and BMI can't see the difference between two people with the same score.
- It's not tuned for every group. Standard BMI ranges were built mainly around adult, non-pregnant, non-elderly populations — it's less reliable for children (who need age-specific charts), older adults, and some ethnic groups where research suggests different risk thresholds.
What else to look at
If you want a fuller picture than BMI alone, two simple extra measurements help:
- Waist circumference. A higher waist measurement (commonly flagged above ~94cm/37in for men and ~80cm/31.5in for women, though guidelines vary) is linked to higher health risk, independent of BMI.
- Waist-to-hip ratio. Divide waist measurement by hip measurement — a higher ratio suggests more fat carried around the middle rather than the hips, which research links to more risk.
None of these — including BMI — replace an actual check-up. They're useful self-tracking signals, not diagnoses.
So is BMI still worth checking?
Yes, with the right expectations. For most people who aren't unusually muscular, BMI is a quick, free, reasonably useful first signal — especially for tracking your own trend over time rather than comparing to someone else. Just treat a single BMI number as a starting point for a conversation, not a verdict.