Anorexic BMI Calculator
BMI: 0.0
| Classification | BMI Range (kg/m²) |
|---|---|
| Severe thinness | Below 16.0 |
| Moderate thinness | 16.0 – 16.9 |
| Mild thinness | 17.0 – 18.4 |
| Normal range | 18.5 – 24.9 |
This calculator is an educational reference tool, not a diagnostic instrument. BMI alone cannot identify an eating disorder or any other medical condition — that requires evaluation by a healthcare professional who considers your full health history, not just a height/weight ratio. If you or someone you know is struggling with eating, body image, or weight concerns, please reach out to a doctor, and free confidential support is available from the National Eating Disorders Association (NEDA) Helpline.
How This Calculator Works
This tool calculates standard Body Mass Index — weight in kilograms divided by height in meters squared (BMI = kg / m²) — from the height and weight you enter, then places that figure alongside the World Health Organization's published reference bands for low body weight: severe thinness (below 16.0), moderate thinness (16.0–16.9), and mild thinness (17.0–18.4), with 18.5 and above considered the start of the WHO "normal" range. These bands are population-level statistical references used in public health and clinical settings, not thresholds for judging any individual body. The "weight at BMI 18.5 / 17.0" figures simply show what weight, at your entered height, would correspond to those reference points — they are informational markers, not targets or goals.
What BMI Can and Cannot Tell You
BMI is a simple screening ratio. It does not account for muscle mass, bone density, frame size, age, sex, or overall body composition, and it says nothing about a person's relationship with food, mental health, or medical history. A low BMI can arise from many causes, and a BMI within the "normal" range does not rule out disordered eating. For this reason, no BMI calculator — including this one — can diagnose an eating disorder, malnutrition, or any other condition. Eating disorders are serious, treatable medical conditions that are diagnosed by qualified healthcare professionals, not by a number. If this topic feels personal or worrying, talking to a doctor, registered dietitian, or mental health professional is the appropriate next step; the NEDA Helpline is also a supportive, confidential place to start that conversation.
Related Tools
To see how your BMI fits alongside other body-composition estimates, try the general BMI calculator or the healthy weight calculator, which offers a broader weight range based on several established methods rather than a single ratio.
Frequently Asked Questions
Can this calculator diagnose an eating disorder?
No. BMI is only a ratio of weight to height and cannot diagnose an eating disorder, malnutrition, or any medical condition. Eating disorders are diagnosed by healthcare professionals who evaluate a person's full medical, behavioral, and psychological history — not by a single number. If you're concerned about yourself or someone else, please talk to a doctor or contact a helpline such as the National Eating Disorders Association (NEDA) Helpline.
What do the WHO thinness categories mean?
The World Health Organization defines three reference bands below the normal BMI range: mild thinness (17.0–18.4), moderate thinness (16.0–16.9), and severe thinness (below 16.0). These are population-level statistical reference points used in public health surveillance, not individual health verdicts — factors like frame size, muscle mass, and age all affect how BMI applies to a given person.