Understanding BMI: Table, Cut-offs and What the Number Doesn't Show
What the body mass index measures, which cut-offs the WHO uses for adults and why BMI alone is not a diagnosis. With a table by height.
Health & Body3 linked calculatorsReading time: 6 min.
Guidance, not a diagnosis
This article explains reference values and where they come from. It does not replace a medical examination or advice. Different values often apply if you have symptoms, are pregnant, for children and for pre-existing conditions: in that case, talk to your doctor.
The body mass index relates body weight to height. It is quick to work out and comparable worldwide, which is why the World Health Organization (WHO) uses it for statistics on underweight and overweight. For an individual it is a first pointer, not a verdict on health.
Key takeaways
- For adults, the WHO defines a healthy weight as a BMI from 18.5 to below 25, overweight from 25 and obesity from 30.
- The cut-offs are the same for women and men aged 20 and over; children and teenagers are assessed with age-specific reference curves.
- BMI cannot tell muscle from fat and says nothing about where fat is stored.
- A notable value is a reason to talk to your GP, not a diagnosis.
How BMI is calculated
BMI is body weight in kilograms divided by the square of height in metres: BMI = weight ÷ (height × height). The unit is kg/m², usually left out.
Example: 70 kg at a height of 1.75 m. Height squared is 3.0625 m², so the BMI is 70 ÷ 3.0625 ≈ 22.9.
Calculate your BMI
Enter your weight and height; the calculator classifies the result using the WHO cut-offs.
The WHO cut-offs for adults
The WHO places adults into four groups by BMI. The cut-offs are deliberately simple so that countries and studies can be compared.
| BMI | Classification (WHO) |
|---|---|
| below 18.5 | Underweight |
| 18.5 to below 25 | Healthy weight |
| 25 to below 30 | Overweight |
| 30 and above | Obesity |
The cut-offs are statistical thresholds for whole populations. A BMI just above or below a cut-off says little on its own about your personal risk.
BMI table by height
For typical heights, the table shows which weight corresponds to a BMI from 18.5 to below 25, and the weight at which BMI reaches 30. Weights are given in steps of 0.1 kg: the range includes every value that still counts as healthy weight; the last column is the first weight with a BMI of 30 or more.
| Height | Healthy weight | Obesity from |
|---|---|---|
| 150 cm | 41.7 to 56.2 kg | 67.5 kg |
| 155 cm | 44.5 to 60.0 kg | 72.1 kg |
| 160 cm | 47.4 to 63.9 kg | 76.8 kg |
| 165 cm | 50.4 to 68.0 kg | 81.7 kg |
| 170 cm | 53.5 to 72.2 kg | 86.7 kg |
| 175 cm | 56.7 to 76.5 kg | 91.9 kg |
| 180 cm | 60.0 to 80.9 kg | 97.2 kg |
| 185 cm | 63.4 to 85.5 kg | 102.7 kg |
| 190 cm | 66.8 to 90.2 kg | 108.3 kg |
| 195 cm | 70.4 to 95.0 kg | 114.1 kg |
Weight range for your height
The ideal weight calculator shows the range for your exact height.
What BMI does not show
BMI only knows two numbers, so it cannot capture three things:
- Muscle or fat: muscle tissue is heavier than fat tissue. People who do a lot of strength training can have a high BMI without carrying much body fat.
- Where fat is stored: fat around the waist is considered less favourable than fat on the hips and thighs. Waist size relative to height adds this information; the waist-to-height calculator works it out.
- Life stages: during pregnancy, growth and older age, body composition changes. The adult cut-offs fit only to a limited extent then.
Put it in context
Use BMI as a starting point. Whether a value matters for your health also depends on blood pressure, blood tests, exercise, existing conditions and family history. Only a medical examination can assess that.
Children and teenagers
The adult cut-offs do not apply to children and teenagers, because the ratio of weight to height keeps changing as they grow. The WHO therefore compares BMI with reference curves for age and sex: for ages 5 to 19, overweight means more than one standard deviation above the median of the WHO reference, obesity more than two standard deviations above it. Your paediatrician assesses your child's value during regular check-ups.
Frequently asked questions about BMI
What is a normal BMI?
Are the cut-offs different for women and men?
Is a BMI above 25 dangerous?
Can I use the BMI calculator for my child?
Sources
Every figure in this article comes from these primary sources or from the linked calculators, which are based on the same sources.
- WHO: Obesity and overweight (fact sheet, definitions for adults and children) (accessed September 30, 2026)
- WHO Global Health Observatory: Body mass index (BMI), indicators and cut-offs (accessed September 30, 2026)
Full-Stack Developer & Founder of HEADON.pro
Full-stack developer and founder of HEADON.pro. Developer of Rechnerzentrale.