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What Air Filter Do I Need?

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The Short Answer

Most homes need a MERV 8 pleated filter for basic protection, MERV 11 if you have pets or mild allergies, or MERV 13 for severe allergies, asthma, or wildfire smoke. Your filter size is printed on the side of your current filter, typically 16x25x1, 20x25x1, or 20x20x1.

Air Filter Finder Tool

1. Size2. Situation3. Results

What size filter do you have?

Check the side of your current filter. The size is printed on the cardboard frame.

Standard 1-inch filters

Deep pleated 4-5 inch filters

Quick Answers by Situation

What air filter should I buy if I just need basic protection?

The Aerostar Pleated MERV 8 (~$25 for a 6-pack) is the best budget air filter for basic home protection. It's MERV 8, which catches dust, pollen, lint, and carpet fibers. Made in the USA and available in over 50 sizes. If you want a name brand, the Filtrete MPR 600 Clean Living (~$35 for a 6-pack) uses 3M's electrostatic media for the same MERV 8 performance. Both are safe for any HVAC system, including older units. Replace every 90 days.

What's the best air filter if I have dogs or cats?

The Filtrete MPR 1000 Micro Allergen (~$50 for a 6-pack) is the best air filter for pet owners. It's MERV 11, which captures pet dander, fur, and dust mites that basic MERV 8 filters miss. 3M's electrostatic technology actively attracts airborne pet particles. For a lower-cost alternative, the Nordic Pure MERV 12 (~$40 for a 6-pack) actually delivers MERV 12 performance at a MERV 11 price. With pets, replace every 30 to 60 days instead of the standard 90 because pet hair clogs filters faster.

What air filter do I need for seasonal allergies?

The Filtrete MPR 1500 Allergen, Bacteria & Virus (~$60 for a 6-pack) is the top pick for allergy sufferers. Rated MERV 12 by industry standards, it captures pollen, mold spores, dust mites, and fine particles that trigger allergic reactions. It's Bob Vila's number one overall pick and a Consumer Reports top performer. For severe allergies or asthma, the Nordic Pure MERV 13 (~$50 for a 6-pack) offers MERV 13 filtration at a lower price, catching particles down to 0.3 microns including some bacteria.

What air filter should I get for wildfire smoke?

The Filtrete MPR 1900 Ultimate Allergen (~$70 for a 4-pack) is the strongest 1-inch filter for wildfire smoke. It's MERV 13 with the highest smoke particle capture rate in Filtrete's lineup. The EPA recommends MERV 13 or higher for wildfire smoke filtration. For smoke plus odor control, the Nordic Pure MERV 13 + Carbon (~$55 for a 6-pack) adds activated carbon to neutralize smoke smell while maintaining MERV 13 particle capture. During wildfire season, replace filters every 30 to 45 days.

Should I get a 4-inch or 1-inch air filter?

If your HVAC system has a 4 or 5-inch filter cabinet (common with Honeywell, Aprilaire, Lennox, and Carrier systems), always use the deep-pleated size it was designed for. Deep filters last 6 to 12 months instead of 60 to 90 days and hold far more dust. The Filtrete 4-inch MPR 1550 (~$30 per filter) is the best deep-pleated pick, with very good dust and smoke removal per Consumer Reports. The Aprilaire 213 MERV 13 (~$40 per filter) is the premium choice. You cannot use a 4-inch filter in a standard 1-inch slot.

What's the best air filter for most homes?

The Filtrete MPR 1000 Micro Allergen (~$50 for a 6-pack) is the best air filter for most homes. It's MERV 11, which captures dust, pollen, pet dander, mold spores, and dust mites. 3M's best-selling mid-tier filter, it covers the widest range of household needs without restricting airflow. Compatible with virtually all residential HVAC systems. If you're on a tighter budget, the Nordic Pure MERV 12 (~$40 for a 6-pack) delivers slightly higher MERV performance for $10 less per pack. Replace every 60 to 90 days.

Best Air Filters by MERV Rating

MERV 8 — Basic Protection

STARTER

MERV 8 catches dust, pollen, lint, and carpet fibers (particles 3 microns and larger). The lowest-cost quality pleated filter and the safest choice for any HVAC system, including older units. Replace every 90 days.

Aerostar Pleated MERV 8
AerostarMERV 8·6-pack·~$25/6-pack

Cheapest quality pleated filter on Amazon. Made in USA. Available in 50+ sizes.

  • Lowest price for a quality pleated filter (~$4/filter)
  • Made in USA with consistent quality
  • Available in 50+ sizes covering every common dimension
  • Lowest airflow restriction, safe for any HVAC system
  • No electrostatic charging (passive filtration only)
  • Basic cardboard frame (functional but not premium)
  • Only catches particles 3 microns and larger
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Filtrete MPR 600 Clean Living
Filtrete (3M)MERV 8·6-pack·~$35/6-pack

3M's entry-level pleated filter. Electrostatic media for enhanced dust capture.

  • 3M electrostatic media actively attracts dust particles
  • Most trusted and recognized filter brand in America
  • Available in 30+ sizes
  • Consistent manufacturing quality from 3M
  • ~$10 more per 6-pack than Aerostar for the same MERV 8
  • Electrostatic charge fades toward end of filter life
  • Only catches particles 3 microns and larger
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Nordic Pure MERV 8
Nordic PureMERV 8·6-pack·~$30/6-pack

Strong mid-price value. Electrostatically charged with a moisture-resistant frame.

  • Electrostatically charged for better particle capture
  • Moisture-resistant frame resists warping
  • Available in 40+ sizes
  • Good balance of price and performance
  • $5 more per pack than Aerostar
  • Less brand recognition than Filtrete
  • Only catches particles 3 microns and larger
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MERV 11 — Pet Owners & Mild Allergies

MOST POPULAR

MERV 11 captures pet dander, dust mites, mold spores, and fine pollen (particles 1 to 3 microns). The right choice for most homes with pets or seasonal allergies. Compatible with virtually all residential HVAC systems. Replace every 60 to 90 days.

Filtrete MPR 1000 Micro Allergen
Filtrete (3M)MERV 11·6-pack·~$50/6-pack

3M's most popular mid-tier. Best overall pick for most homes with pets or mild allergies.

  • 3M's best-selling mid-tier filter
  • Electrostatic 3-in-1 technology for pet dander and allergens
  • Compatible with virtually all residential HVAC systems
  • Available in 25+ sizes
  • ~$50/6-pack is double the cost of MERV 8 options
  • MERV 11 misses smoke and bacteria (need MERV 13 for those)
  • 2x price of budget filters adds up over a year
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Nordic Pure MERV 12
Nordic PureMERV 12·6-pack·~$40/6-pack

MERV 12 at a MERV 11 price. Hypoallergenic, resists mold and mildew.

  • MERV 12 performance at MERV 11 pricing
  • Hypoallergenic filter media
  • Moisture-resistant frame resists mold and mildew
  • Available in 40+ sizes
  • Less brand recognition than Filtrete/3M
  • MERV 12 slightly more airflow restriction than MERV 11
  • No electrostatic 3-in-1 technology like Filtrete
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Filtrete MPR 1200 Odor Reduction
Filtrete (3M)MERV 11·6-pack·~$55/6-pack

Same allergen filtration as MPR 1000 plus activated carbon for odor elimination.

  • Activated carbon layer eliminates cooking, pet, and smoke odors
  • Same MERV 11 allergen filtration as MPR 1000
  • Only mainstream filter combining particle + odor filtration
  • 3M electrostatic media
  • $55/6-pack is the priciest MERV 11 option
  • Carbon layer saturates faster, replace every 60 days
  • Available in fewer sizes (20+) than other Filtrete lines
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MERV 13 — Severe Allergies, Asthma, Smoke

MAXIMUM

MERV 13 filters particles down to 0.3 microns, catching smoke, bacteria, and virus carriers. The EPA recommends MERV 13 or higher for wildfire smoke and allergen management. Check your HVAC manual before installing. Replace every 60 to 90 days.

Filtrete MPR 1500 Allergen, Bacteria & Virus
Filtrete (3M)MERV 12·6-pack·~$60/6-pack

Bob Vila's #1 overall. Consumer Reports top performer. The gold standard for premium filtration.

  • Bob Vila's #1 overall pick for furnace filters
  • Consumer Reports top performer at high fan speed
  • Captures allergens, bacteria, and virus carriers
  • 3M electrostatic media with premium construction
  • $60/6-pack is a significant step up in cost
  • More airflow restriction than MERV 8 or 11
  • Technically rated MERV 12, not 13 (MPR 1500 bridges the gap)
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Filtrete MPR 1900 Ultimate Allergen
Filtrete (3M)MERV 13·4-pack·~$70/4-pack

Highest-rated 1-inch Filtrete. Strongest smoke and fine particle capture available.

  • Highest MERV rating in Filtrete's 1-inch lineup (MERV 13)
  • Strongest smoke particle capture in a standard filter slot
  • Captures particles down to 0.3 microns
  • 3M's top-tier electrostatic media
  • $70/4-pack is the most expensive 1-inch option (~$17.50/filter)
  • Only 4 filters per pack instead of 6
  • Highest airflow restriction of any 1-inch filter
  • Available in fewer sizes (15+)
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Nordic Pure MERV 13
Nordic PureMERV 13·6-pack·~$50/6-pack

MERV 13 performance at a lower price than Filtrete equivalents. Best value premium filter.

  • Full MERV 13 at ~$50/6-pack ($20 less than Filtrete MPR 1900)
  • 6 filters per pack (Filtrete MPR 1900 only has 4)
  • Electrostatically charged media
  • Available in 35+ sizes
  • Less brand recognition than Filtrete/3M
  • Same high airflow restriction as any MERV 13
  • No activated carbon for odor control
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Nordic Pure MERV 13 + Carbon
Nordic PureMERV 13·6-pack·~$55/6-pack

MERV 13 particle capture plus activated carbon for smoke and odor removal.

  • MERV 13 particle capture plus activated carbon for odors
  • Best single-filter solution for wildfire smoke (particles + smell)
  • 6 filters per pack at $55
  • Available in 30+ sizes
  • Carbon layer reduces particle filtration surface slightly
  • Replace every 60 days (carbon saturates faster)
  • Highest airflow restriction plus carbon layer
Check Price on Amazon →

Deep Pleated (4-5 Inch) — Extended Life

LONG LASTING

Deep pleated filters last 6 to 12 months and hold far more debris than standard 1-inch filters. Requires a compatible 4 or 5-inch filter cabinet (common with Honeywell, Aprilaire, Lennox, and Carrier systems). You cannot use a deep filter in a standard 1-inch slot.

Honeywell Home MicroDefense 4"
HoneywellMERV 8·2-pack·~$25/2-pack

Lasts 12 months. Deep pleats hold 20x more than 1-inch filters. Budget deep-pleated pick.

  • Lasts up to 12 months between replacements
  • Deep pleats hold 20x more debris than 1-inch filters
  • Trusted Honeywell brand
  • Low airflow restriction despite 4-inch depth
  • Only MERV 8 (basic filtration for a premium format)
  • Limited to common 4-inch cabinet sizes
  • Requires a compatible 4-inch filter cabinet
Check Price on Amazon →
Filtrete 4" MPR 1000
Filtrete (3M)MERV 11·2-pack·~$30/2-pack

Deep pleated MERV 11 with 3M electrostatic technology. Replace once every 6-12 months.

  • 3M electrostatic media in deep pleated format
  • MERV 11 captures pet dander and allergens
  • 6-12 month replacement interval
  • Available in common 4-inch cabinet sizes
  • ~$30/2-pack is a higher upfront cost
  • Only available in 2 common sizes (16x25x4, 20x25x4)
  • Requires compatible 4-inch filter cabinet
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Filtrete 4" MPR 1550 Allergen Defense
Filtrete (3M)MERV 12·1-pack·~$30/filter

Consumer Reports: very good dust/smoke removal, nearly unrestricted airflow. Best deep-pleated pick.

  • Consumer Reports: very good dust and smoke removal
  • Nearly unrestricted airflow despite MERV 12 rating
  • Replace once a year for most homes
  • 3M premium electrostatic media
  • ~$30 per single filter (higher per-unit cost)
  • Limited to 16x25x4 and 20x25x4 sizes
  • Requires compatible 4-inch filter cabinet
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Aprilaire 213 MERV 13
#4Best Premium DeepAprilaire 213 MERV 13
AprilaireMERV 13·1-pack·~$40/filter

Consumer Reports: excellent at all fan speeds. Premium deep-pleated pick for Aprilaire cabinets.

  • Consumer Reports: excellent at all fan speeds
  • Full MERV 13 in deep pleated format
  • Designed specifically for Aprilaire filter cabinets
  • 6-12 month replacement interval
  • $40 per single filter is the highest deep-pleated price
  • Primarily fits Aprilaire cabinets (check dimensions for others)
  • Only common in 20x25x4 size
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Nordic Pure 4" MERV 12
Nordic PureMERV 12·2-pack·~$35/2-pack

Value deep-pleated option with MERV 12 performance and moisture-resistant frame.

  • MERV 12 performance in deep pleated format
  • 2-pack at ~$35 is good per-unit value
  • Moisture-resistant frame
  • Available in 3 common 4-inch sizes
  • Less brand recognition for deep-pleated filters
  • No electrostatic technology like Filtrete
  • Requires compatible 4-inch filter cabinet
Check Price on Amazon →

Quick Reference: What Filter Do You Need?

By Your Situation

SituationYou NeedWhy
No pets, no allergies, just basicMERV 8Catches dust and pollen. Lowest cost. Safe for any system.
Pets (cats, dogs)MERV 11Traps pet dander and fur that MERV 8 misses.
Mild allergies (seasonal)MERV 11Captures mold spores, dust mites, fine pollen.
Severe allergies or asthmaMERV 13Filters particles down to 0.3 microns including bacteria.
Smoker in the homeMERV 13Catches smoke particles and neutralizes odor (with carbon).
Wildfire smoke areaMERV 13EPA recommends MERV 13+ for wildfire smoke filtration.
New baby in the homeMERV 11-13Removes fine particles for sensitive developing lungs.
Older HVAC system (15+ years)MERV 8Higher MERV can restrict airflow and strain older systems. Check manual.

By MERV Rating

MERVCatchesMissesBest For
MERV 8Dust, pollen, lint, carpet fibers (3+ microns)Pet dander, mold spores, fine dustBudget homes, older HVAC, renters
MERV 11All of MERV 8 + pet dander, dust mites, mold spores (1–3 microns)Smoke, bacteria, virus carriersMost homes with pets or mild allergies
MERV 13All of MERV 11 + smoke, bacteria, some virus carriers (0.3–1 microns)Requires compatible HVACAllergies, asthma, smoke, new babies

Frequently Asked Questions

What MERV rating air filter do I need?

Most homes do best with MERV 8 to MERV 13. MERV 8 for basic protection, MERV 11 if you have pets or mild allergies, MERV 13 for severe allergies, asthma, or smoke. Don't go higher than your HVAC system can handle. Check your manual for the max MERV rating your system supports.

What size air filter do I need?

Check the side of your current filter. The size is printed on the cardboard frame (e.g., 20x25x1). If it's faded, measure your filter slot: length x width x depth in inches, then round up to the nearest whole number. That rounded number is your "nominal size," which is what you order.

What's the most common furnace filter size?

The most common residential filter sizes are 20x20x1, 16x25x1, 16x20x1, and 20x25x1. The "1" is the standard 1-inch depth that fits most HVAC systems. These four sizes cover roughly 60 to 70 percent of homes.

How often should I change my furnace filter?

Standard 1-inch filters: every 60 to 90 days. Homes with pets, allergies, or heavy dust: every 30 to 45 days. Deep pleated 4 to 5 inch filters: every 6 to 12 months. A dirty filter makes your HVAC work harder, raises energy bills, and worsens air quality.

What is the difference between MERV 8 and MERV 13?

MERV 8 catches particles 3 microns and larger (dust, pollen, lint). MERV 13 catches particles down to 0.3 microns (smoke, bacteria, virus carriers). Higher MERV means better filtration but more airflow restriction. MERV 13 is the highest rating recommended for residential use.

Is a higher MERV rating always better?

No. Higher MERV means denser filter media, which restricts airflow. If your HVAC system can't handle it, you'll strain the blower motor, increase energy costs, and potentially damage the system. Most residential systems handle MERV 8 through 13 fine. Check your manual for the max MERV rating.

What MERV rating do I need for allergies?

MERV 11 minimum for seasonal allergies (pollen, dust mites, mold spores). MERV 13 for severe allergies or asthma, as it captures finer particles including some bacteria. The EPA recommends MERV 13 or higher for managing airborne allergens.

What MERV rating do I need for pets?

MERV 11 captures pet dander, fur, and dust mites that MERV 8 misses. If you have multiple pets or family members with pet allergies, step up to MERV 13. Replace filters every 30 to 60 days with pets because they clog faster.

What air filter do I need for wildfire smoke?

MERV 13 minimum. The EPA specifically recommends MERV 13 or higher for filtering wildfire smoke particles. The Filtrete MPR 1900 (MERV 13) with carbon is a strong choice for combined smoke particle and odor removal.

What's the difference between MERV, MPR, and FPR?

MERV (Minimum Efficiency Reporting Value) is the industry standard, rated 1 to 16. MPR (Microparticle Performance Rating) is 3M/Filtrete's proprietary scale, rated 300 to 2800. FPR (Filter Performance Rating) is Home Depot's scale, rated 4 to 10. Rough equivalents: MERV 8 is about MPR 600 / FPR 5. MERV 11 is about MPR 1000 / FPR 7. MERV 13 is about MPR 1500 to 1900 / FPR 10.

What's the difference between nominal size and actual size?

Nominal size is the rounded number printed on the filter label (e.g., 20x25x1). Actual size is the exact measurement (e.g., 19.5 x 24.5 x 0.75 inches). Always order by nominal size. Filters are designed to be slightly smaller than stated for easy installation into your filter slot.

Can I use a Filtrete filter in a Honeywell system (or vice versa)?

Yes, for standard 1-inch and 2-inch filters. Size and MERV matter, not brand. A 20x25x1 MERV 11 from any manufacturer fits any system with a 20x25x1 slot. For 4 to 5 inch deep-pleated filters, check that the actual dimensions match your specific filter cabinet, as they vary more between brands.