Anorexic BMI CalculatorFree online fitness & health calculator — instant results, no sign-up
Checks BMI against clinical thinness thresholds.
For general information only. This is not medical advice, diagnosis, dosing guidance or a treatment recommendation. Talk to a doctor or other qualified health professional about your health, pregnancy, or diet.
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About the Anorexic BMI Calculator
The Anorexic BMI Calculator calculates an individual's Body Mass Index (BMI) and evaluates it against established clinical thinness cutoffs. It is used to identify whether an individual's weight has dropped into ranges associated with significant underweight status or clinical diagnostic criteria for severe thinness.
- Height
- Standing height in centimeters (cm), typically between 100 cm and 250 cm.
- Weight
- Body weight in kilograms (kg), typically between 20 kg and 200 kg.
Formula and method
BMI = w / (h / 100)^2
- BMIBody Mass Index in kg/m²
- wBody weight in kilograms (kg)
- hStanding height in centimeters (cm)
Height in centimeters is divided by 100 to convert to meters, then squared. Weight in kilograms is divided by the squared height in meters to compute BMI, which is rounded to one decimal place. The unrounded BMI is then classified into one of four clinical categories based on cutoffs at 15.0, 17.5, and 18.5.
Worked example
These are the calculator's starting values and the results it actually produces for them.
Inputs
- Height175 cm
- Weight75 kg
Results
- BMI24.5
- AssessmentNot underweight
How to use the Anorexic BMI Calculator
- 1Divide height in centimeters by 100 to convert the measurement to meters.
- 2Square the height in meters.
- 3Divide weight in kilograms by the squared height to determine the raw BMI value.
- 4Round the BMI to one decimal place and compare against threshold values: < 15 ('Extremely low'), 15 to < 17.5 ('Below clinical threshold'), 17.5 to < 18.5 ('Underweight'), or >= 18.5 ('Not underweight').
Reading your result
The tool outputs your calculated BMI alongside an Assessment category. A result of 'Not underweight' indicates a BMI of 18.5 or higher, while 'Underweight' spans 17.5 to 18.4. Results labeled 'Below clinical threshold' (< 17.5) or 'Extremely low' (< 15) reflect body weights that fall below standard diagnostic markers for severe underweight conditions.
Limitations
This calculator relies strictly on height and weight and does not measure body composition, muscle mass, or bone density. It does not provide a formal medical or psychological diagnosis of anorexia nervosa, which requires clinical evaluation of eating behaviors and psychological factors. It is also not adjusted for age-specific growth percentiles in children and adolescents.
Common questions
Why is 17.5 considered a clinical threshold?+
A BMI below 17.5 has historically been used in diagnostic guidelines, such as the ICD-10, as a physical criterion indicating significantly low body weight in adults.
Can someone have an eating disorder if their BMI is in the 'Not underweight' range?+
Yes. Eating disorders, including atypical anorexia and bulimia, occur across all weight and BMI categories. BMI only reflects physical body mass relative to height, not psychological criteria or nutritional status.
What should I do if my result shows 'Below clinical threshold' or 'Extremely low'?+
A BMI below 17.5 is associated with significant medical risks, including electrolyte imbalances and organ strain. You should consult a qualified physician or healthcare professional for a comprehensive medical evaluation.
Does the calculator save my information?+
Calculations run in your browser. While signed in, inputs and results are automatically recorded in account history; saving a result creates a separate saved record.
Further reading
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Results are estimates for informational purposes and are not financial, medical or legal advice.