Buying A Furnace Filter: Tips & Advice

Let’s talk about furnace filters that are 16 x 25 x 4.

We interviewed three HVAC veterans with a combined 34 years of experience to get their insights. Then we asked our parent readers for their real world suggestions.

Here’s an important piece of advice we learned after spending several hours researching these filters: MEASURE FIRST!

That’s right, it is important to measure your filter box and compare it to the exact dimensions of the filters recommended in this article. 

These filters come in two basic sizes: regular and slim fit. The latter are slightly less than 4″—and as you might have guessed, some furnaces have filter boxes that only work with the slim fit models.

Of course, changing your furnace filter every 90 days helps ensure your furnace runs most efficiently—and it helps with indoor air quality.

But which furnace filter is best for your home? What’s the difference between less expensive and more pricey brands?

Here’s a quick rundown on furnace buying tips and advice:

• Furnace filters have a MERV rating which measures how well it removes particulates from the air. (MERV stands for Minimum Efficiency Reporting Value).

• The higher the MERV rating, the more efficient the filter is at removing smaller particles that contribute to bad air quality (like pollen and pet dander). MERV values range between 1-20.

• After interviewing several HVAC experts, we believe a MERV value between 7 and 13 is best for most residences. 

• The lower the MERV rating, the lower the price (in most cases). A filter with a MERV rating of 1-6 may only remove the largest particles in the air—for example, pet hair (but not dander).

• MERV ratings in the middle (7 to 13) remove fine particles like smoke and bacteria. What about higher rated MERV filters? Those are for medical care facilities or commercial installations where you need to remove even finer particles.

• While 90 days is the general rule, you may want to replace your filter more often in special circumstances. Have a pet that is shedding its fur? Or a wildfire nearby that sent smoke in your backyard? In that case, changing out the filter more often makes sense.

After pouring over third-party research and trying out several brands ourselves, here are our top picks for furnace filters:

About the Authors

Denise & Alan Fields are consumer advocates and best-selling authors. The Fields have authored 12 books with three million copies in print, including the best-selling guide to baby gear, Baby Bargains.

The Fields have been featured and quoted in the New York Times, Wall Street Journal and Los Angeles Times.

As consumer products experts, the Fields have been guests on the NBC Today Show, Good Morning America and ABC’s 20/20.

How We Pick Products To Recommend

We often turn to our readers (3 million strong!) to find products to recommend. We ask our parent readers for their favorites and consider their real-world experiences in our recommendations.

When we test a product, we always purchase it with our own monies. We do not take free samples, as we believe that compromises our independence.

We also fact check manufacturer information with our own measurements. If a maker claims a product weighs X pounds, we will weigh it to make sure. If the battery life is supposed to be six hours, we will see how it stands up in the real world.

In some cases, we will do interviews with experts in the field to get additional feedback on products.

To get hands-on time with products, we regularly meet one-on-one with gear companies and even tour manufacturing facilities. (When we do this, we pay our own travel expenses).

Why Trust Us

We’ve been rating and reviewing products for the home and families since 1994. We do extensive research, evaluating products with an eye toward quality, ease of use and affordability.

We make our living from affiliate commissions, but we always recommend what we think are the best bets for our readers (not the ones that are the most expensive). We are always looking for products that offer the best bang for the buck.

Our independence is a key reason why we have been doing this so long. As we mentioned above, when we purchase a product for hands-on testing, we do so with our own money.

Here’s another key point: we don’t take money from the brands we review. No free samples, no sponsors, no “partnerships.” Our work is 100% reader-supported!