Furnace filter ratings vary.

MERV (Minimum Efficiency Reporting Value) is a standard rating system that measures the effectiveness of air filters used in HVAC (heating, ventilation, and air conditioning) systems. The MERV rating ranges from 1 to 20, with higher numbers indicating better filtration efficiency.

Here is a breakdown of what each MERV rating means:

• MERV 1 to 4: These filters provide minimal filtration and are typically used in residential settings to protect the HVAC system from large particles like dust and lint.
• MERV 5 to 8: These filters can capture smaller particles like pollen, mould spores, and pet dander. They are commonly used in residential and commercial settings.
• MERV 9 to 12: These filters provide even better filtration for smaller particles like bacteria, smoke, and smaller allergens. They are commonly used in commercial and industrial settings.
• MERV 13 to 16: These filters are highly efficient at capturing even smaller particles like viruses and bacteria and are commonly used in hospitals and laboratories.
• MERV 17 to 20: These filters are used in specialized settings like cleanrooms and nuclear power plants where extremely high levels of filtration are necessary.

It’s important to note that higher MERV ratings also mean that the filter will restrict airflow more than lower-rated filters, so it’s important to choose a filter that is compatible with your HVAC system and won’t cause damage or reduce efficiency. Consult an HVAC professional if you are unsure what filter is best for your system.