This number, shown in square feet, tells you how big of a room a certain air purifier can effectively filter.
The larger a room is, the more powerful an air purifier is required to filter the greater volume of air in that room.
To find out the square footage of a room in your house or apartment, multiple the length of the room times the width. For instance, if your room was 10 feet wide by 15 feet long (10 x 15), your square footage would be 150 sq. ft. You would then need an air purifier rated for at least 150 square feet to effectively clean the air in that room.