Q. How do I measure what size air filter I require?
A. Check to see if your furnace or A/C has an existing air filter in it. If so, does it fit properly? If it contains a disposable furnace filter, are there any crushed corners or has the filter been forced into the system to fit? If not, measure the existing filter with a tape measure. That is the replacement size you should be ordering your new HealthSmart air filter.
If the filter does not fit properly, or you do not have an existing air filter in your system, you will have to measure the grill opening or the filter slot of your furnace/air handler.