How to Measure a Room for an Air Purifier

Calculate the size of your room in cubic feet. For a rectangular room, you need three measurements: length, width and height of your room. For example, measuring along your floor gives you a length of 12 feet and a length of 10 feet 6 inches (10.5 feet). Multiply those figures: 12 x 10.5 = 126 SQUARE feet. To turn square feet into cubic feet, measure the height of your room from floor to ceiling; for example, your room is 9 feet high. Multiply your square feet by height: 126 x 9 = 1134 CUBIC feet. This is the measurement to determine the right capacity of your air purifier.

Measure your room in sections if it is not rectangular. You may have an alcove or that jog in the wall where your bedroom backs up to the bathroom. Begin with the biggest area you can turn into a rectangle. For example, ignoring the alcove, your floor measures 12 long by 8 feet wide (12 x 8 = 96 square feet). Measuring the alcove separately gives you an additional space measuring 6 feet long by 3 feet wide (6 x 3 = 18 square feet). Add them together (96 + 18 = 114 square feet). Now the height: 9 feet. Multiply: 114 x 9 = 1026 CUBIC feet).

Come as close as you can when dealing with the lowered ceiling of a bay window, a small curved alcove or other irregularities.
Give it a good guess and, when in doubt, add a little more space (pretend the bay window ceiling is as high as the rest of the room, for example), rather than struggling for a tight fit. An air purifier designed for a very slightly larger room will work more efficiently than one designed for smaller space.

Make some notes about the character of your room. Once you're in the room with the door closed, your measurements are perfect. Then again, there's a door--or maybe more than one. There's an open doorway connecting your room to a dressing room, your exercise area or those fabulous walk-in closets that sold you on the house. More space full of air to clean. Your bedroom is right next to the kitchen or directly over the furnace; french doors lead right out to a terrace; or your house has forced-air heat. All of these factors affect the quality of the air in your room. You should note any special features that may suggest the need for extra work by an air purifier. It's hard to translate these easily into math but write them down before shopping.