4" Furnace Filters - Pack of 6

If you're new to furnace filters, don't worry—we've got you covered. This simple guide will help you understand the basics, including how to choose the right thickness, pick the best MERV rating, and know when it's time to change your filter. Each section links to a deeper resource if you want to learn more.

1. Understanding Filter Dimensions

Furnace filters are sized using three measurements: width × height × thickness—and the last number is the thickness. For example, a filter labeled 16x25x1 is 16 inches wide, 25 inches tall, and 1 inch thick.

These dimensions are specific to your HVAC system. Always check the size listed on your current filter or consult your system’s manual. Choosing the wrong size can reduce airflow and filtration performance.

2. Choosing the Right Filter Thickness

Filter thickness determines how much air a filter can clean and how long it lasts. Thicker filters tend to last longer and hold more dust, but not every HVAC system can fit them.

• 1-Inch Filters: Most common, affordable, and easy to replace. Best for homes with standard air quality needs.

• 2-Inch Filters: Offer better filtration and last longer than 1-inch.

• 4 & 5-Inch Filters: Best for high-efficiency systems and homeowners wanting top-tier air quality with less maintenance.

See our full guide on how to choose the right filter thickness

3. Understanding MERV Ratings

MERV (Minimum Efficiency Reporting Value) tells you how well a filter catches particles.

• MERV 8: Basic protection from dust and pollen. Great for homes without pets or allergies.

• MERV 11: Enhanced protection from smaller particles like pet dander and fine dust.

• MERV 13: Maximum protection from smoke, bacteria, and allergens. Ideal for allergy sufferers and those with respiratory issues.

See our full guide on how to pick a MERV rating that's right for you

4. When to Change Your Filter

How often you should change your filter depends on both its thickness and MERV rating. For example, a 1-inch MERV 13 filter might need to be changed monthly, while a 5-inch MERV 8 filter could last six months.

See our full guide on how often to change your filter

Get Personalized Reminders

Want help remembering when to change your filter? Sign up for our personalized reminder service. Just answer a few quick questions and we’ll send you a schedule tailored to your home and lifestyle.

With this guide, you're ready to make informed decisions and breathe cleaner air every day!

Understanding MERV (Minimum Efficiency Reporting Value) ratings is crucial when selecting the right furnace filter for your home or business. MERV ratings indicate a filter’s effectiveness at capturing airborne particles—the higher the rating, the smaller the particles the filter can trap.

MERV Ratings Guide:

• MERV 8 (Basic Filtration)

  • Ideal For: Residential settings without specific air quality concerns.

  • Captures: Large airborne particles such as lint, dust, pollen, and mold spores.

  • Commonly Used In: Standard homes and apartments.

• MERV 11 (Enhanced Filtration)

  • Ideal For: Homes with pets, allergy sufferers, and businesses seeking better air quality.

  • Captures: Smaller particles, including pet dander, fine dust, and smaller mold spores.

  • Commonly Used In: Homes with pets or mild allergies, office spaces, and commercial buildings.

• MERV 13 (Superior Filtration)

  • Ideal For: Homes or businesses requiring superior air quality, individuals with significant allergies or respiratory conditions.

  • Captures: Very small particles such as smoke, bacteria, viruses, and microscopic allergens.

  • Commonly Used In: Hospitals, medical facilities, homes with severe allergies or asthma, and commercial spaces demanding high air purity.

Factors to Consider When Selecting a MERV Rating:

• Health and Allergy Needs: Higher MERV ratings offer more protection against allergens and contaminants, benefiting allergy sufferers and individuals with respiratory conditions.

• HVAC System Compatibility: Higher MERV ratings can restrict airflow slightly, so ensure your HVAC system supports higher-rated filters.

• Environmental Factors: Consider choosing higher MERV-rated filters if you live in an area with high pollen counts, pollution, or have pets in your home.

By selecting the appropriate MERV rating based on your specific air quality needs and HVAC compatibility, you can ensure healthier air, improved comfort, and better system efficiency.

Filter dimensions are listed in nominal inches (rounded up for convenience). Because every filter must slide freely into its slot, its actual size is slightly smaller. Our table below lists both numbers so you can match what you measure at home to the correct replacement size.