Anorexic BMI Calculator
Assess BMI against underweight and anorexia severity thresholds.
About Anorexic BMI Calculator
This calculator compares a BMI value against the DSM-5 severity specifiers for anorexia nervosa and the WHO underweight threshold. BMI is used in clinical settings as one component of assessing illness severity — not as a standalone diagnostic tool. Anorexia nervosa is a complex condition and a number on a screen does not capture the full picture of anyone's health or worth.
Formulas
BMI
BMI = Weight (kg) ÷ Height² (m²)
- W
- Weight in kilograms
- h
- Height in metres
DSM-5 AN severity thresholds
Mild AN: BMI ≥ 17 | Moderate: 16–16.99 | Severe: 15–15.99 | Extreme: <15
Worked example
With the default values below, Anorexic BMI Calculator returns BMI of 18.37. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Unitsone of Metric (kg, cm), Imperial (lb, in)
- Metric (kg, cm)
- Weight (kg)accepts 20–300 kg
- 50 kg
- Height (cm)accepts 100–250 cm
- 165 cm
- Weight (lb)accepts 44–660 lb
- 110 lb
- Height (in)accepts 39–98 in
- 65 in
Results
- BMI
- 18.37
- Severity Category
- Mild (AN) / Moderately underweight
- Clinical Note
- Mild severity or moderately underweight — professional support recommended.
- Minimum Healthy Weight
- 50.4 kg
- Weight Gain to Healthy Minimum
- 0.4 kg
Step by step
- 1BMI= 18.37
- 2Classification= Mild (AN) / Moderately underweight
- 3Minimum healthy weight (BMI 18.5)= 50.4 kg
Assumptions and limits
- The result is derived only from the 5 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
- This tool is for informational and educational purposes only — it is not a diagnostic tool and does not provide medical advice. BMI is a limited screening measure; only a qualified healthcare professional can assess or diagnose an eating disorder. If you or someone you know is struggling with an eating disorder or body image concerns, please know that help is available and recovery is possible. You deserve support. • National Eating Disorders Association (NEDA) Helpline: 1-800-931-2237 (US) • Crisis Text Line: Text 'NEDA' to 741741 • Beat Eating Disorders (UK): 0808 801 0677 • International resources: www.eatingdisordersolutions.com
- This is an estimate for general information and not professional medical advice. See the full disclaimer for the limits that apply to this kind of calculator.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
This tool is for informational and educational purposes only — it is not a diagnostic tool and does not provide medical advice. BMI is a limited screening measure; only a qualified healthcare professional can assess or diagnose an eating disorder. If you or someone you know is struggling with an eating disorder or body image concerns, please know that help is available and recovery is possible. You deserve support. • National Eating Disorders Association (NEDA) Helpline: 1-800-931-2237 (US) • Crisis Text Line: Text 'NEDA' to 741741 • Beat Eating Disorders (UK): 0808 801 0677 • International resources: www.eatingdisordersolutions.com
Frequently Asked Questions
What do these BMI thresholds mean clinically?
The DSM-5 uses BMI to grade restriction severity: it correlates with metabolic complications (refeeding syndrome risk, cardiac arrhythmia, bone density loss). A BMI below 15 is associated with significant medical risk and typically requires inpatient or intensive outpatient care.
Can someone have an eating disorder at a normal BMI?
Yes — many people with anorexia, bulimia, or ARFID maintain a weight within the normal BMI range. BMI cannot diagnose an eating disorder; that requires a clinical assessment of eating behaviours, cognitions, and medical history. Never use BMI alone to dismiss someone's struggles.
What should I do if I am worried about myself or someone I know?
Reach out to a healthcare provider, therapist, or one of the crisis and support lines listed in the disclaimer below. Recovery is possible with the right support — you are not alone, and asking for help is a sign of courage, not weakness.