What Do Air Filter Ratings Measure?

Man changing his home's air filters

If you’re like most people, you probably think of air filters as a way to keep your home’s air clean and free of allergens. But did you know that there are different types of air filters, and a range of air filter ratings? Welsch Heating & Cooling explains air filter ratings in more detail so you can better understand how these ratings impact your filter choices.

What Do HVAC Air Filters Do?

Air filters play an important role in your home by keeping debris out of your forced air heating and cooling equipment. By doing so, filters keep the inner workings of this equipment clean and reduce system wear and tear as well as malfunctions. Filters also help regulate air flow through the HVAC system for proper performance. As an added bonus, filters remove particle pollution from the air for better indoor air quality.

MERV Rating

When it comes to air filters, MERV is the terminology used to describe and apply a value to the filter performance rating. MERV stands for minimum efficiency reporting value. MERV is a rating system that measures the filter’s ability to capture particles between 0.3 and 10 microns in size. An air filter with higher MERV ratings mean that the filter is more effective at capturing small particles.

The Importance of a Good Air Filter rating

Air filter ratings are important because they measure the air filter’s effectiveness at capturing particles in the air. The higher the rating, the more particles the filter can capture and the better the filter functions at capturing finer particles.

This is important because choosing a filter with good air filter ratings means that the air quality is better in your home. You and your family will be breathing cleaner air, which is crucial for your health. A good air filter can help to reduce asthma symptoms and other respiratory problems. An efficient filter can also protect your HVAC system, keep it running longer, and help keep your utility bills low.

How The Air Filter Rating Can Impact Filter Purchases

It’s important to understand how air filter ratings work before purchasing a filter. Typically, the lower the MERV rating, the cheaper the filter will be. Filters with a high MERV rating are more expensive in many cases.

Air filter ratings are important because they impact how well the filter blocks contaminants from entering your HVAC system and home. The best air filter ratings for most home HVAC systems are MERV 8 to 13. Anything higher than a MERV rating of 13 can actually hinder airflow and damage the HVAC system.

How Often to Replace Your Air Filter

As a homeowner, you’ll need to change your filters regularly to ensure that your HVAC system is getting sufficient air flow and that your home has good indoor air quality. How often to replace your air filter varies depending on the air filter ratings and the quality of your home’s indoor air. Other airborne particles can also get caught in your filter such as pet dander, dust particles, and mold spores can also clog up your HVAC filters faster. Factors like these may require you to do filter replacement more frequently.

Air filters with low air filter ratings may need to be replaced as often as every month, while high-efficiency filters may go 9 to 12 months in between replacements.

Air Filters for Your Home

All air filters are not created equal. When you understand what a MERV rating is and how it can impact the air filtration in your home, you can find the best air filter for your needs. If you need help finding the right air filter for your home’s HVAC system, contact Welsch Heating & Cooling today.


On Sunday evening during the high heat, I called as the a/c was providing warm air.  I received a call that Service was alerted.  Without any intervention on my part, the problem was determined and a new a/c was in operation by 2:00 PM.  That’s “organization”.

Russ B.

Welsch Heating and Cooling has always been a great company for my family’s HVAC needs. Pure professionals!


Just want you to know how very happy we are with the excellent job Mike did on all of our copper gutters/flashing and dormers.

John and Mary P.

Welsch employees have always been professional and helpful. They have provided the best service and solutions possible to all of our needs over the years.


We have used Welsch before. This was part of an annual heating and  annual air conditioning  tune up. We have two air conditioners and furnaces so the price, in my mind was reasonable. ($290 combined for the two inspections and tune ups.) They checked and cleaned the system and checked...

John M.

More Reviews

Service & Emergencies: (314) 567-6347 Call Today!