Ideal Body Weight Estimation — Adults
IBW for overweight or obese adults can be estimated based on the following formula
Female: 45.5 kg + 0.91(height – 152.4 cm) or
45.5 kg + 2.3 kg for each inch over 5 ft
Male: 50.0 kg + 0.91(height – 152.4 cm) or
50 kg + 2.3 kg for each inch over 5 ft
For example, a 90 kg man who is 5’ 5” tall
IBW = 50 + (2.3 x 5) = 61.5 kg
Maintenance fluid= (4 x 10) + (2 x 10) + (1 x 41.5) = 101.5 mL/hr (~2.4 liters/day)
Ideal Body Weight Estimation — Children
There is no consensus on the best method used to calculate IBW for children. If child is overweight or obese (for example, BMI-for- age ≥ 85% and ≥ 95%, respectively), use US growth charts.
Calculate IBW using Body Mass Index Method which defines IBW = [BMI at the 50th percentile for that child's age × (Height in m)2]
For example, the IBW of a girl who is 4 years old and 105 cm tall (BMI at 50th percentile for age/sex is 15.3).2
IBW = 15.3 × 1.05 × 1.05 = 16.9 kg