How to Size a Mastercool

Mastercool evaporative coolers provide efficient and cost-effective cooling for homes in hot, dry areas.

Unlike air conditioner units whose capacity is measured in British Thermal Units (BTUs), coolers are measured in cubic feet per minute (CFM). Whether sizing a unit to cool a single room or an entire house, the calculations are the same. The area to be cooled must be calculated in cubic feet to determine what size cooler is needed.

Measure the width and length of the space to be cooled. Multiply the two numbers together.

Measure the height of the ceiling. Multiply the product of the calculation in Step 1 with the measured height of the ceiling.

Divide the product of the calculation in Step 2 by 2. This value is the CFM required to cool the space.

Things You Will Need

  • Calculator
  • Measuring tape


  • As an example, if your house is 25 feet wide and 45 feet in length with an 8 foot ceiling, the calculations are 25 x 45 = 1125; 1125 x 8 = 9000; 9000 รท 2 = 4500. A house this size requires a cooler that is at least 4500 CFM.