1. Divide the power rating of the fan, measured in kilowatts, by 0.746, a constant conversion value. If the fan, for instance, consumes 5 kW. then 5 divided by 0.746 equals 6.7 horsepower
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A rough number would be 0.8 CFM / sq ft.
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1 Measure the dimensions of your bathroom. Use a tape measure to measure each dimension of your bathroom  the length of each wall and the height from floor to ceiling. For a bathroom
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