Anorexic BMI Calculator
Calculate Body Mass Index (BMI) and determine healthy weight ranges.
Physical Measurements
BMI
Moderately Underweight
Severity Level
Health risk assessment
Weight to Gain
To reach healthy range
Healthy Min
Target range
Healthy Max
Target range
How it works
This tool compares a Body Mass Index against the clinical low-weight thresholds sometimes used as a screening indicator. BMI is weight divided by height squared; a value below 17.5 is often cited as a marker of significant underweight. It is a screening number only, not a diagnosis.
BMI and the low-weight threshold
BMI = kg ÷ m² Underweight < 18.5; severe thinness < 16
- kg
- body weight in kilograms
- m
- height in metres
Worked example
- Weight 45 kg
- Height 1.70 m
- BMI = 45 ÷ (1.70)²
- BMI = 45 ÷ 2.89
BMI ≈ 15.6 — in the severe-thinness range.
Good to know
- BMI alone cannot diagnose an eating disorder, which involves behaviors and psychology, not just weight.
- If you or someone you know may be struggling, please reach out to a doctor or a support line such as the NEDA Helpline.
- Recovery and health are about far more than a number — professional support makes a real difference.
Related Calculators
Frequently Asked Questions
What do BMI categories mean?
Underweight: <18.5, Normal: 18.5-24.9, Overweight: 25-29.9, Obese: ≥30. BMI is a screening tool but doesn't distinguish muscle from fat.
Is BMI accurate for athletes and muscular people?
BMI may overestimate body fat in muscular individuals since muscle weighs more than fat. Consider body composition analysis for athletes.
How can I achieve a healthy BMI?
Focus on balanced nutrition, regular exercise, and gradual weight changes. Consult healthcare providers for personalized advice and safe weight management.
How often should I exercise?
The WHO recommends at least 150 minutes of moderate-intensity or 75 minutes of vigorous-intensity aerobic activity per week.
What is a balanced diet?
A balanced diet includes variety from all food groups: fruits, vegetables, whole grains, lean proteins, and healthy fats.
How much water should I drink?
General recommendation is 8-10 glasses (2-2.5 liters) per day, adjusted for activity level and climate.
How important is sleep?
Sleep is crucial for physical recovery, mental health, and overall wellbeing. Adults need 7-9 hours nightly.