The reason is that 1-inch filters have a small surface area compared to the 5’’ ones. No, you can not use a 1-inch filter instead of a 5. Frequently Asked Questions (FAQs) Can I use a 1-inch filter instead of 5? Knowing the real size will help you buy the correct air filters. Here is an air filter comparison chart given below to make things more clear: Normal Size (inch) You’ll get to know the real measurements. It doesn’t matter how tall or wide the filter you’re using, simply multiply the numbers above. This measurement is true for filters in all types of sizes. To understand the actual size, you have to multiply each of the sides with specific numbers. Whenever you see something like 16x25x4 on a filter, it doesn’t represent the actual size. Check out the next section to know what a filter size actually looks like. And make sure to measure the perfect air filter size.ĭon’t worry, I already got the size sorted for you. Try to use filters that are closest to the slot size.

So, using too big air filters is not really recommended. As a result, the air won’t be purified at all. The efficiency level will drop down.Īs a consequence, the furnace will heat for a longer/shorter period of time than expected.Įventually, you’ll know there’s something wrong. The heating and cooling system will not work properly. But it’ll definitely bring some changes.Īnd you’ll know about this by going through the utility bill.

I’m not saying it’ll destroy your machine. Having the wrong size filter can impact the performance of your HVAC. Well, did you notice a 5-inch filter takes longer to replace than a 4-inch one? That’s right, the thicker your filter is, the more time it takes. So, you can see that it’s like a 3-month cycle depending on each size. Take a look at the average replacing times of air filters below- Filter Size When Should You Change Your Furnace Filter?Īs we’ve already learned, 16x25x4 and 16x25x5 filters are swappable. But when you should think about changing it and what should be the changing frequency? Anybody can! But only if it matches right with the size of the furnace. So, can I use a thinner furnace filter? Yes, I can. Just like in these cases, thinner filters are better than thicker ones. In this case, going for a 3’’ filter would be the best idea instead of 5. Suppose, your furnace has only 3 inches in thickness. You have to think less about maintenance too!īut in some cases, thinner air filters work the best.

Thick air filters last longer than thin ones. The reason people care about thickness is that thicker filters allow more filtration. Well, when we’re talking about replacing thickness, obviously we’ll think about performance. However, if your Onix tubing has issues, the 4-inch filters won’t work properly. Its fiberglass material is supposed to be 20 times more efficient than others.

Honeywell Home 16x25x4 MERV 8 is another great choice.

They offer good quality 4-inch MERV 8 and MERV 11 air filters.

Aerostar 16x25x4 MERV 11 Pleated Air Filter– It’s well-made and durable to prevent any kind of dust and smoke.

If you’re good to go with 16x25x4 filters, here are some of the highly recommended 4-inch filters by users like you.

The air won’t bypass too much unless you have a different furnace size. So, what happens in a 4-inch vs 5-inch air filter? Though there’s a 1-inch gap, you’ll see a 4’’ HVAC filter fits in a 5’’ slot. If it’s too much, it’s bad for the health of your HVAC. Here, you should be concerned about how much airflow is bypassed.

Actual size for 4 inch air filter