How this calculator works
The Baldwin equations predict vital capacity from height and age, with a separate coefficient for each sex. Height is the dominant term and age reduces the prediction. The output is a reference value for a healthy person of the same sex, age and height, not a target and not a measured vital capacity. Modern pulmonary function laboratories usually report predicted values from the Global Lung Function Initiative (GLI) equations instead. This page uses the older Baldwin equations because they are short, public and reproducible, and it states that limitation rather than presenting them as the current clinical standard. The result is an estimate for information only and is not medical advice.
Formula
Male predicted vital capacity (mL) = (27.63 - 0.112 x age in years) x height in cm. Female predicted vital capacity (mL) = (21.78 - 0.101 x age in years) x height in cm.
Worked example
A 40-year-old man of 175 cm has a coefficient of 27.63 - 4.48 = 23.15, so the predicted vital capacity is 23.15 x 175 = 4051.25 mL, or about 4.05 L. A 60-year-old woman of 160 cm has a coefficient of 21.78 - 6.06 = 15.72, giving 2515.2 mL, or about 2.52 L.
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Frequently asked questions
Is this my measured vital capacity?
No. It is a predicted reference value from height, age and sex. Enter a measured value in a spirometry interpretation tool to calculate a percentage of predicted.
Why use the 1948 equations?
They are short, published and easy to reproduce. Contemporary laboratories generally use GLI-2012 prediction equations, which include ethnicity and use more complex terms.
What age range is supported?
The page accepts ages 18 to 80, which covers the adult range in which the equations are commonly applied. It does not predict values for children.
Can I solve for height from a vital capacity?
This page predicts vital capacity only. The omni structure record also listed a reverse direction; that mode is not claimed here because the measured value would need the same manoeuvre conditions as the reference equation.