Bests & Worsts Reviews from Amazon

The 22” and 28” GermGuardians are the highest price per cfm (cubic foot per minute) of the leading HEPA filters on Amazon GermGuardian AC4825 puts out 21 cfm of air, at $4.62/cfm GermGuardian AC5000E puts out 26 cfm of air at $5.73/cfm Honeywell 1700 puts out 134 cfm of air at $0.75/cfm Honeywell 50250 puts out 266cfm at $0.48/cfm Whirlpool AP51030K puts out 600 cfm of air at $0.48/cfm I hope this helps someone make an informed purchasing decision. The numbers you see listed in the product description are air exchanges per hour in square feet. Notice Honeywell states air exchanges per 12 minutes (5x/hr) in square feet. So if you compare the square feet, it is not apples to apples. The real comparison is cfm.