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BMI calculator
Calculate your Body Mass Index from your height and weight, with the World Health Organization weight category.
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).
Plan meals around these numbers
NutraPlanner turns targets like these into branded meal plans for your clients — or yourself.