You size an evaporative cooler by cubic feet per minute (CFM) — multiply your home’s square footage by the ceiling height, then divide by two. So a 2,000 sq ft home with 8-foot ceilings needs roughly 8,000 CFM. Most single-family homes in the Spokane area fall between 4,500 and 7,500 CFM.

Quick sizing rule

  • (Square footage × ceiling height) ÷ 2 = required CFM
  • Add 10–20% capacity for sunny, west-facing homes
  • Up to 4,500 CFM for small ramblers and condos
  • 4,500–6,500 CFM for typical 1,500–2,200 sq ft homes
  • 6,500–8,500 CFM for larger or two-story homes

Sizing also depends on duct layout, attic ventilation, and whether the cooler will be roof-mounted or ground-mounted. We size and install swamp coolers based on a Manual J-style load calculation, and we can compare evaporative cooling to central AC installation if you want a side-by-side cost analysis.