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

• Sepsis and Septic Shock BundleAt least 30 mL/kg crystalloid in the first 3 h (actual weight; adjusted or ideal if BMI >30)
• Electrolyte ImbalancesRefeeding syndrome (ASPEN 2020) is a fall in phos, K or Mg of 10–20% (mild), 20–30% (moderate), or over 30% or with organ dysfunction (severe) within 5 days of restarting calories. High risk includes BMI under 16 or little intake for over 7 days.

Related calculators

• 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.