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Tidal Volume Calculator

Health

Calculate predicted body weight and reference tidal volume from height and sex, using the standard lung-protective ventilation formula instantly.

Reviewed by the thecalcu.com team · Last updated July 25, 2026

120210
410

Predicted Body Weight (PBW)

61.4
Reference Tidal Volume
369

This calculator computes your Predicted Body Weight (PBW), Reference Tidal Volume from the values you enter.

Inputs
HeightSexReference Tidal Volume
Outputs
Predicted Body Weight (PBW)Reference Tidal Volume

What is a Predicted Tidal Volume?

The Tidal Volume Calculator computes predicted body weight (PBW) from height and sex, then applies a reference mL-per-kg figure to estimate a lung-protective tidal volume reference value. This is an educational tool for understanding the standard height-based approach used in ventilation reference literature, not a ventilator setting tool.

For related pulmonary reference calculators, see the Lung Capacity Calculator and Vital Capacity Calculator.

Why Use a Tidal Volume Calculator?

Understanding why tidal volume targets are based on predicted body weight rather than actual weight is a foundational concept in respiratory physiology and critical care education. This calculator demonstrates that calculation instantly from height and sex.

Who Should Use This Calculator?

  • Students of respiratory therapy, nursing, or critical care medicine learning the PBW-based tidal volume concept.
  • Healthcare educators demonstrating the standard predicted body weight formula.
  • Anyone researching how lung-protective ventilation reference values are derived.
  • Researchers working with predicted body weight methodology.

What Insights Does the Tidal Volume Calculator Give You?

The Predicted Body Weight (PBW) is the primary building-block result, derived from height and sex using the standard formula. The Reference Tidal Volume applies your chosen mL/kg figure to that PBW, illustrating how a lung-protective volume target is calculated in reference literature.

How to use this Predicted Tidal Volume calculator

  1. Enter the height in centimetres.
  2. Select the sex.
  3. Adjust the reference tidal volume per kg (commonly 6-8 mL/kg).
  4. Read the Predicted Body Weight and Reference Tidal Volume instantly.
  5. Remember this is an educational reference only, actual ventilator settings are determined by a qualified critical care team.
Show formula & methodology ↓Show less ↑

Formula & Methodology

Predicted Body Weight (Male) = 50 + 2.3 × (Height in inches − 60)

Predicted Body Weight (Female) = 45.5 + 2.3 × (Height in inches − 60)

Reference Tidal Volume = PBW × mL/kg

Worked example, a man 178 cm (70.1 in) tall, using 6 mL/kg:

PBW = 50 + 2.3 × (70.1 − 60) = 50 + 23.2 = 73.2 kg

Reference Tidal Volume = 73.2 × 6 = 439 mL

Frequently Asked Questions

What is predicted body weight (PBW) in ventilation?
Predicted body weight is a standardized weight estimate based on height and sex, used as the reference basis for calculating lung-protective tidal volume targets, it deliberately doesn't use actual body weight, since lung size correlates more closely with height than with weight.
Why is tidal volume calculated from height instead of actual weight?
Lung volume correlates much more closely with height than with actual body weight, especially in people who are overweight or underweight, so using a height-based predicted body weight avoids over- or under-estimating appropriate tidal volume for lung size.
What is a commonly referenced tidal volume target?
A commonly cited lung-protective ventilation reference range is 6-8 mL per kg of predicted body weight, which is why this calculator defaults to 6 mL/kg as a starting reference point.
How is predicted body weight calculated?
The calculator uses the standard formula: for men, 50 + 2.3 × (height in inches − 60); for women, 45.5 + 2.3 × (height in inches − 60), converting your entered height in centimetres to inches first.
Is this calculator a ventilator setting tool?
No, this is an educational reference calculator only. Actual mechanical ventilation settings must be determined and adjusted by a qualified critical care team based on the patient's full clinical picture, not a general online calculator.
Why does sex affect predicted body weight?
The formula reflects average physiological differences in body composition between sexes at a given height, which is why separate reference constants are used for men and women.
Can I adjust the mL/kg reference figure in this calculator?
Yes, the calculator lets you adjust the mL/kg reference value, since different lung-protective ventilation protocols may reference slightly different target ranges within the commonly cited 6-8 mL/kg window.
How is this related to the Lung Capacity Calculator?
The [Lung Capacity Calculator](/lung-capacity-calculator/) predicts total lung capacity from height and sex, while this calculator uses a related height-based reference (predicted body weight) specifically to estimate a lung-protective tidal volume target.
Why doesn't this calculator use age as an input?
The standard predicted body weight formula used as the basis for lung-protective tidal volume targets is based on height and sex only, without an age term, reflecting its original derivation.
What unit is tidal volume measured in?
Tidal volume is expressed in millilitres (mL), the standard unit used in ventilator settings and respiratory physiology.
Also known as
predicted body weight calculatorlung protective ventilation calculatorPBW tidal volume calculator6 mL per kg calculator