It’s easy to get lost while shopping for air filters. The extensive number of options to choose from and technical terminology can be overwhelming. Let’s make it easier. We’ve put together an air filter shopping guide to help make air filter shopping quick and painless.

Air Filter Terms to Know

There are a few technical terms you will come across when shopping for air filters:

MERV stands for Minimum Efficiency Reporting Value. Residential air filters commonly have a MERV rating which represents a measurement of how effective a filter is at removing particles from the air. A higher MERV rating means that an air filter is more effective at removing smaller particles from the air. In other words, filters with higher MERV ratings will filter the air more thoroughly.

Over the last few years, there has been a lot of buzz about HEPA filters due to the global pandemic. HEPA filters, or High Energy Particulate Air filters, are made of a much finer mesh than other filters. This allows them to screen out 99.97% of teeny tiny particles as small as 0.3 microns in size. This can include filtering allergens, pollen, dander, mold spores, bacteria, and even viruses like COVID-19.

The size is just the size, right? Not so simple. Air filter manufacturers often make filters to measure slightly smaller than their slot to allow them to slide into place without getting damaged. Air filters are extremely delicate and can get damaged easily, which could compromise effectiveness. Additionally, there are slight variations in size by brand. As a result, your air filter has two important sizes – an ‘actual size’ and a ‘nominal size.’​

  • ACTUAL SIZE: You guessed it – the actual size of an air filter is what you’d find if you measured it with a ruler. On some filters, you may find the actual size printed in small text on the side of the frame.
  • NOMINAL SIZE: The nominal size is the big, bold, advertised size you’ll see on air filter packaging and air filter frame. Nominal size is the rounded-up whole-number of the actual, measured size. Due to all of the potential variations in actual size, nominal size helps streamline shopping for air filters.

MPR stands for Microparticle Performance Rating. FPR stands for Filter Performance Rating. These are alternatives to MERV Rating. You might come across MPR or FPR when shopping specific brands or retailers.


How to Choose the Right Air Filter

We’ve got your answers to the most frequently asked questions of air filter shopping.

Why Are There So Many Air Filter Size Options?

There are an extensive number of air filter sizes available because HVAC equipment comes in all different shapes and sizes. Purchasing the correct air filter size is essential for reaping all the benefits your air filter has to offer. If your air filter is not the right size, air will flow around it rather than through it, which means the air won’t get filtered.

Air filter sizes are measured in inches and expressed as dimensions. Your air filter size will be in the same format as example 14 x 20 x 1. The nominal size of the example air filter is 14 inches by 20 inches by 1 inch.

What Air Filter Size Do I Need?

The easiest way to identify your air filter size is to look at the label of the existing air filter.

  • On most air filters, the size is printed right on the side of the frame. Once you know the old air filter’s size, you can purchase a new filter with the same dimensions.
  • If your old air filter doesn’t have the measurements printed on the frame, you can measure the filter yourself. While measuring, keep in mind the difference between actual size and nominal size. You’ll need to round your measurements up to the nearest inch to find the dimensions of the filter you need. 

If you don’t have an old filter handy, we can help! A Varsity Home Service technician would be happy to advise on your air filter size.

What Air Filter Brand Should I Buy?

When shopping for air filters, you will come across a large difference in prices across different sizes, filtration levels, and brands. Brand is a less important factor when shopping for air filters. What really matters when choosing a high-quality air filter are the MERV rating and the material.

What MERV Rating Is Best?

Choosing the right MERV rating can be tricky because you will need to strike a balance between maximizing indoor air quality and system efficiency. Since a high MERV rating means a higher level of air purification, your instinct may be to choose the highest MERV rating to maximize filtration. However, a very important factor to consider is that most standard residential HVAC systems can’t handle the air filter density that comes along with highest MERV ratings.

An air filter with too high a MERV rating can impair your HVAC equipment's efficiency because it forces the equipment to work harder to push the air through. When your HVAC system has to work harder, it uses more energy, increases run time, and strains components of the system. The key to successful air filter shopping is to maximize your indoor air quality without compromising your system’s performance.

For the average home, we generally recommend a range of MERV-6 to MERV-12 rating depending on your home’s air filtration needs. One way to simplify MERV ratings is to group them into levels. For example:

  • MERV-1 TO MERV-4 – Limited Filter – Large particles only (e.g. dust mites, carpet fibers, sanding dust).
  • MERV-5 TO MERV-8 – Basic Filter – Recommended for homes with average air filtration needs. Filters common dust mites, pollen, textile fibers, larger mold spores, dust lint, and similar sized particles.
  • MERV-9 TO MERV-12 – Premium Filter – Recommended for homes with pets and/or household members with allergies or respiratory issues. Filters most mold spores, pollen, dust mites, textile fibers, dust lint, lead dust, smog, fine dust, pet dander, and similar sized particles.
  • MERV-13 to MERV-16 – Exceptional Filter – Recommended for homes with household members suffering from severe allergies, respiratory illnesses, or other related conditions. Filters bacteria, viruses, tobacco smoke, auto fumes, pet dander and other microscopic particles.

What MERV Rating Do I Need?

  • If your home has average air filtration needs, MERV-8 could be a great option for you. MERV-8 rated air filters come in almost any size and block most common household particles.
  • If members of your household are susceptible to allergies, asthma or other respiratory conditions, an air filter with a MERV rating of 10 to 12 could be a great choice for you. MERV-10 to MERV-12 rated filters can remove most allergy-causing particles from your home’s air and may help relieve related symptoms.
  • If you’re considering a higher rating air filter (MERV-13 or above), let us know! A Varsity Home Service technician can review your system specifications and discuss your options with you.

Where to Buy Air Filters

Our top recommendation for choosing an air filter retailer is to make sure you’re shopping with a reputable company. The quality of the air you breathe has a tremendous impact on your health, and you want to make sure your efforts to protect your home’s air quality are worthwhile. You can find air filters at most home improvement stores and on websites that sell home improvement products.

You can also buy your air filters directly through Varsity Home Service in our Online Store

  • We offer over 300 different air filter options and free 2-3 day shipping directly to your home. 
  • One of our favorite features of the Online Store is the option to sign up for auto-delivery. When you sign up for auto-delivery, we automatically send your new air filter when it’s time to change it, so you can take that task off of your ‘to-do’ list.

Replacing Your Air Filter

No matter where you choose to shop for your air filters, we can take care of your filter replacement for you. When you have your new air filter on-hand for your maintenance visits, our technicians will happily replace them as a courtesy service. You can conveniently book your next maintenance appointment online right here on our website. 

Beyond Air Filters

Air filter replacement isn't the only step you can take to sanitize your home’s air. There are a number of whole-home indoor air quality options for your home, including ionizers, UV lights, air scrubbers, air purifiers, ventilation systems, humidifiers, dehumidifiers, and more. Give us a call to learn more – the Varsity Team would be happy to discuss indoor air quality options with you.