Use BMI cutoffs for underweight severity screening and care-escalation conversations.
Overview
This calculator applies standard BMI math and highlights low-BMI thresholds often discussed in severe underweight screening contexts.
It is not a diagnostic tool for anorexia nervosa. Diagnosis requires a qualified clinical assessment including behavioral and psychological criteria.
Steps
Use recent measured values in consistent units.
Compute kg/m^2 from weight and height.
Compare against underweight severity ranges.
Repeated declines may indicate rising risk.
Include menstruation, labs, vitals, and behaviors.
Seek professional care for concerning results or symptoms.
Math
BMI = weight(kg) / height(m)^2
BMI quantifies weight relative to height. Very low values can flag serious nutritional risk, but diagnosis requires more than BMI.
Worked cases
BMI = 42 / 1.70^2 = 14.53
BMI 14.5 suggests very high medical risk; urgent evaluation is advised
BMI = 47 / 2.8224 = 16.65
BMI 16.7 is underweight and warrants full assessment
BMI drops from 18.0 to 16.5
Rapid decline indicates elevated concern and need for timely care
Why use this
Questions