Absolute humidity and dht22?

Question

Arduino

There is an article on Habré ( habrahabr.ru/post/244135/), where the dude did the ventilation of the garage by calculating the absolute values ​​​​of humidity. One sensor stands on the street, the other inside the garage, it measures relative humidity and temperature, but he did not provide any explanations and formulas, he only gave a link www.pogoda.by/glossary/?nd=3&id=24
and wrote that he allowed an error of 0.01 in difference in sensor readings.
The question is how to calculate the absolute humidity, knowing the relative percentage and temperature, so as not to waste electricity on the ventilation fan.

Answer 1

At school, in natural history, they were taught to translate relative humidity into absolute. As Artem said , it is enough to simply make a two-dimensional plate of the dependence of the density of saturated water vapor in air on pressure and temperature.
Then, taking readings of relative humidity, atmospheric pressure and air temperature, it will be easy to calculate the density of water vapor in the air.
Just do not forget about atmospheric pressure.
Otherwise, you get a display meter from the category of "brick on a rope."