Body Metrics

BMI Calculator

Weight relative to height, a quick screen for underweight, overweight and obesity.

Reviewed by Alex G, BSN, RN, CEN, CCRN, CMC, NREMT-P · From the Reference tab of the app

Turn on JavaScript to use this calculator, or open it in the web app.

Formula

Weight / (Height/100)^2

How it is used

• < 18.5: Underweight
• 18.5 - 24.9: Normal weight
• 25 - 29.9: Overweight
• ≥ 30: Obesity

• In the ICU, morbid obesity impacts medication dosing (use Ideal Body Weight vs Actual Body Weight depending on drug lipophilicity) and ventilator mechanics (requires higher PEEP).

Same formula as the app. Open it in the web app.

Related one-pagers

• ICU Nutrition and RefeedingBMI · 16–18.5 · <16
• CEN Mental Health: Crisis, Suicide Risk, Eating Disorders and AbuseAtypical anorexia · Same, at normal weight after rapid loss · Same instability; BMI does not rule it out
• Sepsis and Septic Shock BundleAt least 30 mL/kg crystalloid in the first 3 h (actual weight; adjusted or ideal if BMI >30)
• Bleeding, Reversal, HIT and DICEnoxaparin 40 mg SC daily (30 mg if CrCl under 30); trauma often 30 mg twice daily; BMI 40 or more often 40 mg twice daily.

Related calculators

• Adjusted Body Weight
• BSA (Mosteller)

For education and exam preparation only. Follow your institution’s protocols. For education and exam preparation only. Verify results independently and follow your institution’s protocols. Not a substitute for clinical judgment.