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Predicted body weight and lung-protective tidal volume (ARDSnet)

Also called PBW, ideal body weight, IBW, 6 mL/kg tidal volume, ARDSnet tidal volume

Predicted body weight from sex and height, with 6, 7 and 8 mL/kg PBW tidal volumes as in the ARDS Network protocol.

Sex

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Formula and scoring

Male PBW = 50 + 2.3 × (height in inches − 60); female PBW = 45.5 + 2.3 × (height in inches − 60). (2.3 kg per inch ≈ 0.91 kg per cm above 152.4 cm.)

Exam and ward pearls

  • ARMA trial (NEJM 2000): 6 vs 12 mL/kg PBW cut mortality from 39.8% to 31.0%.
  • Tidal volume is set on height and sex, never on actual weight – a 120 kg patient of 160 cm gets the same VT as a 60 kg one.

When not to rely on it

  • The formula is a linear extrapolation; below about 152 cm (60 in) it gives progressively smaller weights. Not for children.

Source

  1. Acute Respiratory Distress Syndrome Network. Ventilation with lower tidal volumes as compared with traditional tidal volumes for acute lung injury and the acute respiratory distress syndrome. N Engl J Med. 2000;342(18):1301-8. doi:10.1056/NEJM200005043421801 · PMID 10793162
  2. NIH NHLBI ARDS Clinical Network. Mechanical Ventilation Protocol Summary (6 mL/kg card, 2008 update). Link

Formula and cut-offs checked against these sources on 8 Nov 2026. Educational tool for clinicians; it does not replace clinical judgement.

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