Ideal Body Weight (IBW) Calculator

About this calculator

This calculator estimates ideal body weight (IBW) using the widely used Devine formula: for men, 50 kg + 2.3 kg for each inch of height over 5 feet; for women, 45.5 kg + 2.3 kg for each inch over 5 feet. Devised by Dr. B.J. Devine in 1974 originally to guide drug dosing, it remains the most commonly cited clinical formula despite being a rough population-level estimate rather than a personalized health target.

Clinicians and hospital pharmacists use IBW (rather than actual body weight) to calculate dosing for certain medications — especially anesthetics and some antibiotics — where dosing on actual weight in overweight or obese patients would risk overdose. Dietitians and fitness professionals also reference it as a rough benchmark, though body composition, frame size, and muscle mass matter more for individual health assessment. Enter height and sex to get the estimate.