Enter your details above to see your result.
How it works
BMI is your weight in kilograms divided by the square of your height in metres. It's a quick population-level screen, not a diagnosis — it doesn't distinguish muscle from fat or account for build, age, or ethnicity.
| Category | BMI |
|---|---|
| Underweight | < 18.5 |
| Normal weight | 18.5 – 24.9 |
| Overweight | 25 – 29.9 |
| Obese | ≥ 30 |
How it's calculated
Body Mass Index divides your weight in kilograms by the square of your height in metres (kg/m²). We then place the result in the World Health Organization adult categories: underweight (< 18.5), normal (18.5–24.9), overweight (25–29.9), and obese (≥ 30).
How to use this calculator
- Enter your details — such as age, weight, and height — in the fields above.
- Choose any options that apply, like your activity level, goal, or formula.
- Read your result instantly. It updates as you type — no sign-up required.
Sources: World Health Organization. Body mass index (BMI) classification for adults.
These calculators give general estimates for healthy adults and are not medical or dietary advice. For individual guidance, consult a registered dietitian or your healthcare provider.
Reviewed by the NutraPlanner nutrition team. · Last updated 2026-06-17
Frequently asked questions
What is a healthy BMI?
For most adults, a BMI between 18.5 and 24.9 is classed as the normal-weight range by the World Health Organization. Below 18.5 is underweight, 25–29.9 is overweight, and 30 or above is obese.
Is BMI accurate?
BMI is a quick population-level screen, not a diagnosis. It doesn't distinguish muscle from fat or account for build, age, sex, or ethnicity, so very muscular or older people can be mis-classified. Use it alongside other measures.
How is BMI calculated?
BMI is your weight in kilograms divided by the square of your height in metres (kg/m²).