BMI calculator
Estimate your body mass index from your height and weight. It’s a rough screening number that ignores muscle and build — not a diagnosis — shown neutrally, with no alarmist signals.
BMI = weight (kg) ÷ height (m)²
Your details
kg
cm
BMI is an approximate indicator and does not account for body composition (muscle, bone). It is not a diagnosis.
Your body mass index
22.9
Within range
This figure is for reference only. For an individual assessment, consult a specialist.
Results are for reference only and are not medical advice. For individual guidance, consult a doctor or dietitian.
Next step
Turn the number into a result
This estimate is just a starting point. In the RESET app it becomes a personal plan that counts calories and macros for you, and Premium unlocks transformation programs.
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How this calculator works
Briefly and honestly: the science behind it, how far you can trust it, and its limits.
How it works
Body Mass Index divides your weight by your height squared and maps the result to a WHO category: underweight (<18.5), normal (18.5–24.9), overweight (25–29.9), obesity (≥30).
BMI = weight (kg) ÷ height (m)²
What it’s based on
The index was proposed by the Belgian scholar Adolphe Quetelet back in the 1830s (hence the “Quetelet index”). The modern threshold categories are standardised by the WHO and CDC.
✓
Is it validated?
BMI is validated as a population screening tool: across large groups it correlates with weight-related risks, which is why the WHO and CDC use it for classification.
Can you rely on it?
It is a reference, not a diagnosis. BMI doesn’t distinguish muscle from fat or account for fat distribution, so it can mislead for athletes, pregnant people and older adults. For an individual health assessment, see a doctor.
Results are for reference only and are not medical advice. For individual guidance, consult a doctor or dietitian.
For the curious
Deeper: why it works this way, what it does for your body, and what happens if you get it wrong.
BMI emerged as an attempt to describe the “average” build of a population with a single number. It doesn’t measure fat directly — it only relates weight to height, which is why it works best across large groups rather than for one person.
What matters for the body isn’t the index itself but what usually sits behind it: the amount and distribution of fat tissue, muscle mass and activity level. That’s why two people with the same BMI can be in very different health.
Relying on BMI alone misleads both ways: a muscular athlete lands in “overweight” despite low body fat, while someone with low muscle mass reads “normal” while carrying too much fat. So read BMI together with waist circumference, how you feel, and a doctor’s assessment when needed.
Worked examples
Concrete numbers for common situations — so you can see at a glance how to read the result.
Woman, 165 cm, 60 kg
- Inputs
- 60 ÷ (1.65)²
- Result
- BMI ≈ 22.0 — normal range
Falls in the 18.5–24.9 band the WHO treats as the normal range for adults.
Man, 180 cm, 95 kg
- Inputs
- 95 ÷ (1.80)²
- Result
- BMI ≈ 29.3 — overweight
Close to the 30 threshold. With high muscle mass BMI can overstate risk — read it alongside waist circumference.
Man, 175 cm, 55 kg
- Inputs
- 55 ÷ (1.75)²
- Result
- BMI ≈ 18.0 — below normal
Slightly under 18.5. A prompt to check that nutrition is adequate — not a diagnosis.
FAQ
Frequently asked questions
What BMI is considered normal?
On the WHO scale the normal range for adults is 18.5–24.9. Below 18.5 is underweight, 25–29.9 overweight, and 30+ obesity. It is a screening reference, not a diagnosis.
Is BMI accurate for athletes?
Not always. BMI doesn’t separate muscle from fat, so a muscular person can read as “overweight” with low body fat. For athletes it’s better to also look at body composition and waist circumference.
Does this calculator work for children or during pregnancy?
No. Children and teens use age-and-sex percentiles, and standard BMI categories don’t apply during pregnancy. In these cases follow your doctor’s guidance.
How do I lower my BMI safely?
BMI moves with weight, so a moderate calorie deficit, enough protein and regular movement help. Crash dieting backfires — a steady pace is more reliable. This is general information, not medical advice.
What to read and do next
Go deeper with articles and turn the numbers into a plan in the app.
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