Tidal Volume Calculator
Enter sex and height to estimate lung-protective tidal volume from ideal body weight.
Educational use only — not medical advice. This tool is for education only. It estimates lung-protective tidal volume from ideal body weight and is not medical advice or a ventilator order. Ventilator settings must be set and adjusted by qualified clinicians for the individual patient.
Lung-protective tidal volume is based on ideal body weight, not actual weight, at 6 to 8 millilitres per kilogram. Ideal body weight comes from height using the Devine formula. For example, a man 70 inches tall has an ideal body weight of about 73 kg, giving a tidal volume range of roughly 438 to 584 mL.
⚠️ Double-check important results. This is an educational estimate, not professional advice — and where it uses a rate, bracket or fee, those change over time. Verify anything you'll rely on, especially in legal, financial, tax or medical matters, and read our full disclaimer. Think a result is wrong? Tell us so we can fix it.
How to Use This Calculator
Select the patient's sex and enter their height in inches. The calculator first estimates ideal body weight using the Devine formula, then multiplies it by 6 and 8 millilitres per kilogram to give the lung-protective tidal volume range.
Tidal volume is set from ideal body weight rather than actual weight because lung size tracks height, not how much a person weighs. Using actual weight in an overweight patient would over-inflate the lungs.
How the Calculation Works
The Devine formula gives ideal body weight in kilograms from height: a baseline of 50 kg for men or 45.5 kg for women at 60 inches, plus 2.3 kg for every inch above that.
Lung-protective ventilation, established by the ARDSNet trials, targets 6 to 8 mL per kilogram of that ideal body weight, with 6 mL/kg used for injured lungs. Multiplying IBW by 6 and by 8 gives the recommended range.
IBW male = 50 + 2.3·(height in − 60); female = 45.5 + 2.3·(height in − 60)
Worked Example
A man 70 inches tall: ideal body weight is 50 + 2.3 × (70 − 60) = 50 + 23 = 73 kg. The tidal volume range is 6 × 73 = 438 mL up to 8 × 73 = 584 mL.
For lung injury, the lower end near 6 mL/kg (about 438 mL) is preferred to protect the lungs.
Assumptions and Limitations
- Uses ideal body weight from the Devine formula, not actual weight
- Targets the 6–8 mL/kg lung-protective range; 6 mL/kg for ARDS
- Height entered in inches; IBW returned in kilograms
- A clinical estimate — ventilator settings require a clinician
When to Use a Tidal Volume Calculator
Respiratory therapy and critical-care learners use this to find a lung-protective tidal volume from ideal body weight. It helps with ventilator-management study and quick reference for the 6–8 mL/kg range. It is an educational tool for understanding lung-protective ventilation, not a substitute for clinical assessment and orders.
Related Calculators
mg to mL Calculator
Convert a drug dose in milligrams to a volume in millilitres using its concentration.
Open calculator →IV Drip Rate Calculator
Find IV drip rate in drops per minute and mL per hour.
Open calculator →Maintenance Fluid Calculator (Holliday-Segar)
Daily and hourly maintenance IV fluids by the 4-2-1 rule.
Open calculator →Caffeine Half-Life Calculator
See how much caffeine remains in your body over time.
Open calculator →Frequently Asked Questions
Why is tidal volume based on ideal body weight?
Because lung size depends on height, not actual weight. Using ideal body weight prevents over-inflating the lungs of an overweight patient, which is central to lung-protective ventilation.
What is a lung-protective tidal volume?
It is 6 to 8 mL per kilogram of ideal body weight, with 6 mL/kg targeted in acute respiratory distress syndrome (ARDS), based on the ARDSNet trials that reduced ventilator lung injury.
What is the Devine formula?
It estimates ideal body weight from height: 50 kg (men) or 45.5 kg (women) at 60 inches, plus 2.3 kg per inch above 60. It is the standard basis for weight-based ventilator settings.
What tidal volume for a 70-inch man?
Ideal body weight is about 73 kg, so the lung-protective range is roughly 438 mL (6 mL/kg) to 584 mL (8 mL/kg), with the lower end preferred for injured lungs.
Can I use this to set a ventilator?
No. It is an educational estimate. Actual ventilator settings must be chosen and continuously adjusted by qualified clinicians based on the specific patient and their gas exchange.
Looking for a different calculator?
CalculatorPlus has free tools across finance, construction, math, health and more — each one showing the formula and a worked example.