Under the WHO adult classification, a BMI of 18.5 to 24.9 counts as normal weight, 25 to 29.9 as overweight, and 30 or above as obese. BMI (body mass index) is your weight in kilograms divided by the square of your height in meters — a quick screening number, not a measurement of body fat itself, so treat it as a starting point rather than a verdict.
Suppose you put the default values into BMI Calculator:
Plug those into the formula BMI = mass (kg) / height (m)² and the result is:
With the defaults of 5 ft 10 in and 168 lb, height converts to 1.778 m and weight to about 76.2 kg. Dividing 76.2 by 1.778 squared (about 3.16 square meters) gives a BMI of 24.1, which sits near the top of the WHO normal range of 18.5 to 24.9 — about six pounds of gain (to roughly 174 lb) would tip the label to overweight, which says more about how sharp the category cut-offs are than about any real change in health.
| Category | BMI range |
|---|---|
| Underweight | below 18.5 |
| Normal weight | 18.5 – 24.9 |
| Overweight | 25.0 – 29.9 |
| Obese | 30.0 and above |
WHO adult classification · Source: WHO BMI classification
BMI was developed in the 1830s by Adolphe Quetelet and adopted by WHO as a population-level screening tool. We use the standard adult formula (mass / height²). For children, BMI must be interpreted against age- and sex-specific growth percentiles — use a pediatric reference instead.
References: WHO BMI classification.
Last reviewed July 2, 2026 · Editorial policy