BMI Calculator (Category & Healthy Range)
Enter age, sex, height, and weight to get BMI, WHO category, healthy weight range for your height, and child percentile when applicable.
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Your result
0.0kg/m²
Category
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- Underweight< 18.5
- Normal weight18.5 – 24.9
- Overweight25 – 29.9
- Obesity I30 – 34.9
- Obesity II35+
Screening only. Not a substitute for medical assessment.
Understanding your BMI result
BMI is a simple screening tool. A value between 18.5 and 24.9 is generally considered a healthy range for adults. It does not distinguish between muscle and fat, so athletes may have a high BMI despite being fit. Always consider your overall health with a doctor.
Want context on what this BMI result means for your decisions?Read the guide →BMI categories (adults, 20+)
Many health bodies use ranges similar to the ones below. Ours follow the same idea:
| Category | BMI range (kg/m²) |
|---|---|
| Severe thinness | < 16 |
| Moderate thinness | 16 – 17 |
| Mild thinness | 17 – 18.5 |
| Normal | 18.5 – 25 |
| Overweight | 25 – 30 |
| Obese (class I) | 30 – 35 |
| Obese (class II) | 35 – 40 |
| Obese (class III) | > 40 |
BMI categories (children and teens, 2–19)
For kids and teens, BMI is compared to growth charts by age and gender. Categories are based on percentiles:
| Category | Percentile range |
|---|---|
| Underweight | < 5th |
| Healthy weight | 5th – 85th |
| At risk of overweight | 85th – 95th |
| Overweight | > 95th |
How it's calculated
BMI (metric): weight in kg divided by height in metres squared.
BMI Prime is your BMI divided by 25. A value of 1 means you're at the upper end of the "normal" range; above 1 means above that range.
Ponderal index uses height cubed instead of squared. It can be useful for very short or very tall people.
Risks linked to a high BMI
A high BMI over time is linked to a higher chance of conditions such as high blood pressure, type 2 diabetes, heart disease, stroke, joint problems, sleep apnoea, and some cancers. It can also affect mood and day-to-day activity. None of this is guaranteed. It's about risk. Talking to a doctor helps you understand your own situation and what to do next.
Risks linked to a low BMI
A very low BMI can mean too little body mass for good health. That may increase the risk of weak bones, low immunity, fatigue, and in women, problems with periods and fertility. In children and teens it can affect growth. If you or someone you know is very underweight, a healthcare provider can check for causes and suggest a safe way to gain weight.
Limitations of BMI
BMI is a rough guide. It does not measure body fat directly or where fat is stored. Very muscular people can have a high BMI without excess fat. Older adults often have more body fat for the same BMI than younger adults. In children, growth and puberty also affect how BMI should be read. So BMI is best used as one of several tools, not the only one. For a full picture, health professionals use other measures and your medical history.
FAQ
What is a good BMI?
For most adults, a BMI between 18.5 and 24.9 is considered normal.
Is BMI accurate?
BMI is a useful population-level indicator but does not account for muscle mass, bone density, or body composition. It can be less accurate for very muscular or elderly people.