How to Find the Right HVAC Filter Size

Your furnace and condenser are some of the most important appliances in your home. If you want to protect your HVAC system, it’s important to keep up with regular system maintenance, including changing the air filter. This small part plays a big role in the overall health of your home and HVAC system.

While we discourage a lot of DIY HVAC fixes, changing the air filter is one you can do on your own. Here’s what you need to know to choose the right HVAC filter size and type. If you think you need professional guidance, contact a professional.

Why Does the Air Filter Size Matter?

Choosing the right size air filter is important for your HVAC’s health and function. If the air filter is too big, you can’t simply cut it down to size. This leaves gaps that allow contaminants into your home.

Conversely, getting a filter that’s too small will leave gaps and compromise your air quality. Always make sure you have the right size air filter.

Look at Your Existing Air Filter

If you have your current HVAC air filter, you can look at it to choose the size for the replacement. Most filters list the size on the side in small print, including the length, width, and depth in inches. In most cases, they’re listed in that order.

One common air filter size is 16x24x1. This represents a 16-inch x 24-inch x 1-inch filter. Most filters come in the same range of sizes, so it should be simple to find the appropriate replacement for your current air filter.

Measure It Yourself

Not every air filter will have printed sizes on the edge. If you can’t find the size of your filter, you can measure it and figure out the appropriate size using the actual measurements of the length, width, and depth. Note the orientation of the filter to make sure you get the right replacement.

The dimensions that you measure will be slightly smaller than the actual size dimensions you need. That same filter with a size of 16 inches by 24 inches by one inch may measure as 15.5 inches by 23.5 inches by .5 inches. Round the number up to the nearest inch, since filter sizes aren’t going to be strange number increments.

Measure Air Register or Air Filter Slot

If you can’t measure the size of the filter directly, which may happen if you have no filter currently, you can measure the slot it goes into. This also requires a little math, but it’s straightforward.

The air filter slot will measure as the size of the filter itself, not the dimensions of the replacement you need. You will need to round up to the nearest inch to get the right measurement for your replacement filter.

Where Is the Air Filter Located?

Most HVAC air filters are found on the return air intake. This is near the return duct where the intake enters your HVAC system. Typically, you’ll find a plate that covers the air filter slot.

Some HVAC systems won’t have an air filter on the air handling unit. If yours is like this, you may find the air filter on the return vent where it enters you home. If you can access the area safely, you can change the air filter by yourself without professional assistance.

Know Your Air Filter’s MERV Rating

When you determine the size of your air filter, you will need to check the MERV rating. All air filters use a MERV rating to measure their effectiveness for filtering out small particles in the air and protecting air quality. A higher MERV rating means the filter does this better than others and removes most environmental contaminants.

Higher ratings aren’t always best, however. Higher MERV filters will capture more pollutants, but they do diminish the efficiency of your unit. These filters are much thicker, which means your HVAC system needs to work much harder to push air through your home. As a result, you may have higher energy bills.

A MERV rating of 5 to 8 is appropriate for most homes. This is enough to capture pollen, dust, mold, dander, and other environmental contaminants. You will still get good efficiency from your unit as well. You will still need to change your filter regularly, however.

If you or someone in your home has respiratory conditions like allergies or asthma, then you may want to opt for a MERV rating of 10 or 12 to keep the air cleaner. These ratings are effective at capturing allergen particles like pollen, exhaust, and mold down to one micron. Remember, this means less efficiency overall, so you may see an increase in your energy bills as a result.

Do you need regular HVAC maintenance or repairs, contact us at JW Heating and Air to schedule your appointment!