How to Calculate Air Cleaner Size

When purchasing an air cleaner, match the correct cleaner size to your room. An air cleaner rated too small will not properly filter the air and run inefficiently; one that is too large only wastes money. For best results, use the size as a guide to direct you to the range of air cleaners available. Use this formula regardless of the type of air cleaner you wish to purchase.

Measuring tape
Calculator (optional)
Pen and paper

Instructions

- 1
  Measure the length and width of the room in feet. Write these values down on a sheet of paper.
- 2
  Multiply the length and width together to determine the square footage of the room. For instance, a room measuring 10 feet by 10 feet would have a square footage of 10 x 10 = 100 square feet.
- 3
  Multiply the square footage (area) of the room by 0.75 to get the clean air delivery rate (CADR) needed for that space. The example room of 100 square feet would need an air cleaner with a CADR of 100 x 0.75 = 75.
- 4
  Use the CADR number to find an air cleaner correctly sized for your room. Round the number up to the nearest CADR air cleaner available. Rounding the CADR number up to the nearest available air cleaner prevents you from purchasing a cleaner too smaller for the space. No danger exists from operating an air cleaner larger than what you need for a room, aside from the slightly higher cost.
- 5
  Look for the CADR on the package information or product description for an air cleaner. You can also consult the CADR chart, with the ratings of all air cleaners on their Website.

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