How to use the predicted lung capacity calculator
Estimate predicted forced vital capacity. Enter height, age, sex in the fields above; the predicted fvc is computed instantly and plotted on the chart so you can see how the answer changes.
Common searches this calculator answers include “normal spirometry”, “fvc prediction”, “lung size”, “calculate predicted lung capacity”, “find predicted fvc”.
Formula
Variables
- h — Height (cm)
- a — Age (years)
- s — Sex (—)
Worked example
With height = 175 cm, age = 30 years, sex = Male, the calculator gives predicted fvc ≈ 4.0765 L.
Tips for accurate results
- Enter height in centimetres, not inches.
- Predicted values come from population reference equations; compare with the reference set your lab or clinic uses.
- Interpret spirometry results with a clinician, since a single predicted value does not diagnose a condition.
Common mistakes
- Applying an adult equation to children or to very tall or short adults outside the equation's range.
- Comparing an estimate with a measurement taken with a different spirometer or protocol.
- Treating a predicted value as a personal target.
Frequently asked questions
What is the predicted lung capacity calculator used for?
Estimate predicted forced vital capacity. It helps with questions such as “normal spirometry”, “fvc prediction”, “lung size”.
What is the formula for the predicted lung capacity calculation?
Predicted FVC (L) = s===1?0.0443 × h-0.0262 × a-2.89:0.0309 × h-0.0211 × a-0.1. Here h is height (cm), a is age (years), s is sex (—).
What inputs do I need for the predicted lung capacity calculator?
You need height in cm, age in years, sex in —. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use the predicted lung capacity calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the predicted lung capacity result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.