# Exhaled air and lung capacity

I wonder if there is any connection between exhaled air and lung capacity. I need to implement some algorithm in my game to calculate points of how much time you blow and compare it maybe with some sportsman.

First of all nice idea! Secondly, wikipedia has very nice graph to answer your question (Image courtesy: wikimedia commons)

Look at the caption below figure in wikipedia for specific details. You will get all values you want plus how to calculations.

[Note: Sorry, I am not able to interpret why X axis is sinusoidal]

• [It's sinusoidal because the x-axis is time and it's a graph of a person breathing] Nov 6, 2015 at 14:40
• Thanks! I thought so, but what's up with sudden bump ? Nov 6, 2015 at 14:42
• They're taking a really deep breath. Nov 6, 2015 at 14:43

There is.

At a first approximation the total lung capacity is the anatomical dead space(the volume of your trachea, more or less) + the tidal volume(the volume of each breath). It's slightly more complicated than that based on the differences in how deep you breathe and how often you can breathe, but at a first approximation exhaled air + half a liter(plusminus) = lung capacity.

• The way this is worded is confusing. The exhaled air you are referring to is from a maximal inspiration to a maximal expiration, also known as FVC or forced vital capacity. FVC + another 1/2 liter is a good good approximation of total lung volume. Nov 6, 2015 at 14:32
• Is is, but I figured I'd gloss over most of it given the precision implicit in the question. If the speed of expiration isn't being measured "how much time you blow" won't give you an accurate representation of FVC at all. And the total lung volume is only first-order related to the VO2max, which you could meaningfully compare to athletes. Nov 6, 2015 at 14:42