How to select Air Conditioner for Room

Hi steemains
Now i am going to show you how to select Air Conditioner for room. we know that AC select in TON so how can you find how much ton of ac is suitable for Room.
we know that in day by day global warming effect is increasing so has effect on temperature that's why temperature is increasing. so doing comfort human being AC is necessary for every human being.
I have a formula by using that every human being can select AC.

if you have diffrent methods for select AC then reply me.