Lung size depends on height and sex, not on actual weight, so ventilator volumes are based on predicted body weight. Low tidal volume ventilation cut mortality in the landmark ARDSNet trial.
How to use the Tidal Volume Calculator
- Sex
- Height
Results update as you type, and every field accepts the units shown in its menu.
How it works
Enter sex and height (measured, or estimated from arm span or knee height if the patient cannot stand).
Inputs explained
| Field | What to enter |
|---|---|
| Sex | Choose one: Male, Female |
| Height | Units: cm, in, m, ft, mm |
What each result means
- Tidal volume at 6 mL/kg = 6×[Predicted body weight]
- At 7 mL/kg = 7×[Predicted body weight]
- At 8 mL/kg = 8×[Predicted body weight]
- At 4 mL/kg (severe ARDS minimum) = 4×[Predicted body weight]
Example values
How the main result changes when Height changes and everything else stays at the example values above:
| Height (cm) | Tidal volume at 6 mL/kg (mL) |
|---|---|
| 87.5 | -54 |
| 131.25 | 185 |
| 175 | 423 |
| 218.75 | 662 |
Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.
Formula
Predicted body weight: men 50 + 0.91 × (height cm − 152.4); women 45.5 + 0.91 × (height cm − 152.4)
Tidal volume = 6–8 mL per kg of predicted body weight (6 mL/kg in ARDS)
Worked example
Inputs — Sex: Male; Height: 175 cm.
Results — Predicted body weight = 70.6 kg; Tidal volume at 6 mL/kg = 423 mL; At 7 mL/kg = 494 mL; At 8 mL/kg = 565 mL; At 4 mL/kg (severe ARDS minimum) = 282 mL.
Key terms
- PBW
- Predicted body weight.
Frequently asked questions
Why use predicted body weight?
Lung size is determined by height and sex, not body fat.
What is low tidal volume ventilation?
6 mL/kg PBW with plateau pressure below 30 cmH₂O.
Is 8 mL/kg safe?
It is the upper limit generally recommended outside ARDS.