ventilation
IBW (female) = 45.5 + 2.3 × (Height in inches − 60)
Normal: Variable by height
Normal: Patient-specific
Female IBW uses the same formula structure as male but starts at 45.5 kg for 5 feet of height (versus 50 kg for males). This difference accounts for average gender-based differences in muscle mass and lean body composition relative to height.
Same indications as male IBW — primarily for tidal volume calculation during mechanical ventilation. Always use height-based IBW rather than actual weight. When height cannot be measured directly, use arm span (approximately equal to height in most patients).
5'5" female (65 inches)
→ 57 kg
TV range: 228–456 mL; ARDS target 342 mL
5'8" female (68 inches)
→ 63.9 kg
TV range: 256–511 mL; ARDS target 383 mL
Critically important for ventilator tidal volume calculations in women, who are statistically more likely to be exposed to excessive tidal volumes if actual weight is used (women may have higher body fat percentage at any given BMI, while lung size is determined by height).