How Long Does a 20x25x4 Air Filter Last?

Learn how long 20x25x4 air filters last and how often they should be changed for optimal indoor air quality.

How Long Does a 20x25x4 Air Filter Last?

Fortunately, most 20x25x4 air filters have a lifespan of between six and eight months. This means that the average homeowner will only need to purchase two of these filters in a year. However, it is recommended that one-inch air filters be changed every two to three months. Pleated air filters are more expensive initially, but they are also more efficient at trapping particles and can last up to 90 days, depending on usage.

Finding air filters for HVAC systems in big box stores can be difficult, so I started ordering them online two years ago. It is generally recommended that cheaper fiberglass filters be changed every 30 days. Children are more sensitive than adults to indoor air pollutants, such as mold, dust mites, dander and pollen, so using quality air filters and replacing them before they become too clogged and dirty is essential for creating a healthy home environment. I use them in my electronic air purifier, which I obviously turned off while changing the filter.

It can be hard to remember when to change your air filter, so it is important to understand how often you should do it in the first place. If you live alone without pets and with good quality outdoor air, then the manufacturer's recommendations for changing the filter should work well for you. If someone in your household has allergies, then more frequent air filter changes are beneficial. If your house has a lot of dust, then one- and two-inch filters should be changed every month, four-inch filters every two months, and five-inch filters every three months.

A clean filter is necessary to prevent dust from passing through the HVAC system and accumulating in the internal coils of the air conditioner, which can reduce its efficiency. Most air conditioning and heating stores charge twice as much for the filter and also require a service charge. We tried a large box store filter before and noticed a huge difference in terms of the amount of suspended dust that was trapped in the filter. During this summer's wildfires, I was able to filter the air inside my house to make it safe to breathe.

If you have allergies or live in an area with poor outdoor air quality, then you should change your filter every 6 weeks to maintain good indoor air quality. I have allergies and have found that Honeywell Merv 12 filters work best for me. As air passes through a building's HVAC system, air filters trap and collect large and small particles such as dust, allergens, and microorganisms. Generally speaking, an air filter with a higher MERV rating is more effective and has a wider application; however, most residential homes will find the best use of an air filter between MERV ratings 5 to 13.