If you happen to buy air filters that may not be the right size for your central heating and a/c and they are too big, one thing you can do if you do not want to go through the hassle of returning them is to cut them, and yes, this method absolutely can work because I have done it a few times.
Sometimes when you buy air filters for a central heating and a/c that is in a home you are renting, you may not know the exact size and try to estimate, but when this happens there could be mistakes.
So the one thing you can do like I said is to cut them to fit. The main thing you need to do is cover the air vent possibilities of your central heating and a/c with the air filters. That is the way air filters work, and of course if you want to avoid having to alter the air filters you buy all together you can just check your central heating and a/c’s air vent and air filter areas and find out the exact size of the air filters you need by measuring it all with a tape measure. That is what the best thing to do is if you do not want to mess with having to alter the air filters for your central heating and a/c unit. This is what I most recently did because I was tired of having to cut the air filters to my central heating and a/c unit when I would buy the wrong sized ones.