BMI & Health Calculator
Body mass index with the healthy range for your height — and an honest note on what the number can and cannot tell you.
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How it works
BMI divides weight by the square of height. It was designed in the nineteenth century to describe populations, not individuals, and it remains a screening indicator rather than a diagnosis.
Its main blind spot is that it cannot distinguish muscle from fat, or say anything about where weight sits on the body. A trained athlete and someone carrying visceral fat can return identical numbers, which is why waist measurement and body composition are better individual guides.
BMI = weight (kg) ÷ height (m)²
- Under 18.5 — underweight
- 18.5 – 24.9 — healthy range
- 25 – 29.9 — overweight
- 30 and above — obese
Worked example
Someone 175 cm tall weighing 78 kg
Inputs
Results
A little over the threshold. Losing 2 kg would land inside the healthy band — although at this margin the number alone means very little.
Frequently asked questions
Is BMI accurate for me personally?
Only as a rough screen. It cannot tell muscle from fat, ignores where weight sits on the body, and reads differently across ages and ethnic groups. Waist circumference and body composition are considerably more informative for an individual.
Do the categories apply everywhere?
No. Several health authorities use lower thresholds for South and East Asian populations, where cardiometabolic risk rises at a lower BMI. The bands shown here are the standard international ones.
Does BMI work for children or athletes?
Not well for either. Children are assessed against age-and-sex percentile charts instead, and muscular athletes routinely land in the "overweight" band at low body fat. Treat those results as noise.
Is my data sent anywhere?
No. The calculation runs entirely in your browser. Nothing you type is transmitted to us or stored.
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