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Air filter pressure drop FAQ

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What is the relationship between filter pressure drop and air flow rate?

A filter’s pressure drop directly corresponds to a filter’s air flow rate. The higher the pressure drop the more restrictive the filter is to air flow. The lower the pressure drop the easier it is for air to flow through the filter. This is important to consider when choosing a filter for your application and your HVAC unit. Most current home HVAC units can accommodate a filter with a MERV 13 or lower. A 1” MERV 13 pleated filter has a pressure drop of around 0.27, and a 1” MERV 8 has a pressure drop of around 0.14.air filter element quotation - Jiatecairfilter

How does filter pressure drop affect flow rate?

When you air filter is installed, it is a barrier between your HVAC and your ducts/vents. When your HVAC system is running the filter slows and limits the air that is being pulled through your vents and ducts. The amount of the HVAC’s air flow slowed by the filter is equivalent to the filter’s pressure drop. Typically, the higher the MERV rating, the higher the pressure drop and the more restrictive the air flow is. Pressure drop directly corresponds to a filter’s air flow rate.

Does the material (ex: fiberglass) affect the pressure drop of the filter?

Filters use various types of medias depending on the application or what the environment requires. A filter’s material type and efficiency rating affect the pressure drop and resistance to air flow. For example, a household pleated filter that uses synthetic media will have a lower pressure drop than a micro-fiberglass media that is used in critical environments such as a hospitals and datacenters.

Pressure drop comparison - merv 8, merv 11, & merv 13

The higher the filtering efficiency rating (MERV rating), the higher the pressure drop.  This also means that as the MERV rating goes up, the more particles and contaminants the filter can capture. Below is a chart comparing the pressure drop of standard 20X24X1 MERV8, 11, and 13 at 1000 CFM. Most current household HVAC units/handlers can handle a MERV 6-13 pleated filter with ease. Always refer to your HVAC systems manufacturer’s guide prior to changing your air filter.


Nominal Size

Actual Size


Pressure Drop



19-1/2” X 23-1/2” X 3/4”





19-1/2” X 23-1/2” X 3/4”





19-1/2” X 23-1/2” X 3/4”



Do higher merv rated filters restrict air flow?

The higher the MERV rating the more efficient the filter is at filtering out and capturing air particles and contaminants. As the MERV rating increases the media typically becomes loftier and thicker, to capture more air pollutants, with this you could see slightly more air restriction. However, we use a pleated accordion style media, that allows us to effectively increase the filter’s surface area without having a high pressure drop or restricting air flow. Most current household HVAC units/handlers can handle a MERV 6-13 pleated filter with ease. Changing your air filters regularly will prevent filters from being loaded and overly restrictive.

What pressure drop is safe for my ac/air handling system?

The accepted pressure drop is different for each air conditioning or air handling system, and you should always refer to your manufacturer’s guide prior to inserting replacing your air filter to ensure you are using the appropriate filter. Most current household HVAC units/handlers can handle a MERV 6-13 pleated filter with ease.

Each air filter has its own unique pressure drop. Even filters sharing the same MERV rating may have differing pressure drops. Many pleated HVAC air filters can still have a high MERV rating, while not drastically restricting air flow. Always refer to your air handler manufacturer’s guide before changing your air filter.

Hepa, ulpa, & ashrae filter pressure drop

The pressure drop for highly efficient filters like HEPA, ULPA, and ASHRAE tends to be higher, they use a quality filter media that is excellent at capturing pollutants and fine particles. HEPA, ULPA, and ASHRAE filters are typically used in commercial and industrial environments or in applications.

Additional factors affecting pressure drop

A filter’s pressure drop changes throughout it’s use. As a filter traps and gathers airborne contaminants the filter’s pressure drop increases and air flow decreases. Frequent filter changeoutsare necessary to reduce the possible negative effects a loaded filter can have on your HVAC equipment.

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