MERV 8 vs 11 vs 13: which furnace filter to buy

MERV tells you how well a filter captures particles of different sizes. Higher MERV captures a larger share of smaller particles and adds more airflow resistance. Pick a rating your system can handle, then buy the printed size for your slot.

What MERV means

MERV stands for Minimum Efficiency Reporting Value. It comes from the ASHRAE 52.2 test method. The U.S. EPA summarizes it as a way to compare how well furnace and HVAC filters capture particles between 0.3 and 10 microns (µm).

The higher the MERV number, the better the filter is at trapping the particle sizes listed for that rating. A 1-inch MERV 13 is not HEPA. We do not claim health outcomes from any MERV rating.

MERV 8, 11, and 13 side by side

These average capture efficiencies are from EPA’s MERV table (ASHRAE 52.2 framing). They are performance bands for the filter media, not guarantees for a whole-house result.

MERV	EPA average capture efficiency (particle size)	What that means when you shop
8	≥20% of 1.0–3.0 µm; ≥70% of 3.0–10.0 µm	Common pleated 1-inch replacement when the equipment manual does not call for higher
11	≥20% of 0.30–1.0 µm; ≥65% of 1.0–3.0 µm; ≥85% of 3.0–10.0 µm	Mid-grade 1-inch pleat (Filtrete MPR 1000 is commonly labeled MERV 11)
13	≥50% of 0.30–1.0 µm; ≥85% of 1.0–3.0 µm; ≥90% of 3.0–10.0 µm	Higher-efficiency option EPA highlights when the fan and slot can take it

Source: U.S. EPA, “What is a MERV rating?”, last updated 14 Jan 2026. Filtrete also prints an MPR number; MPR is 3M’s scale, not MERV. Home Depot’s FPR is a third scale. Compare MERV to MERV.

How to choose (EPA language)

Higher MERV means more resistance to airflow. EPA’s guidance for upgrading is to choose a filter with at least MERV 13, or as high a rating as your system fan and filter slot can accommodate. If you are unsure what your furnace or air handler will tolerate, ask an HVAC technician. Follow the filter manufacturer’s replacement interval so the panel does not load up and restrict flow further.

1-inch slots — MERV 8, 11, and 13 are all sold as ordinary 1-inch pleats. Confirm fit on the size page (actual cut varies by brand).
Thicker media cabinets (4-inch / 5-inch class) — deeper media often runs at higher MERV with less pressure drop than a thin 1-inch MERV 13. See 16x25x4 and the other 4- and 5-inch pages.
Do not force a thickness change to chase MERV. A 16x25x1 does not replace a 16x25x4 media cartridge.

Buy by size first, then MERV

The printed size on the frame is what has to match the slot. After you know the size, pick MERV. Full size pages have actual dimensions by brand, the same EPA table, and dated pack tables where we checked prices:

16x25x1 — common furnace slot · MERV 13 comparison
20x20x1 — common return grille
20x25x1
16x20x1
Thicker media where higher MERV is common: 16x25x4, 20x25x4, 16x25x5

Need the tape measure first? How to measure a furnace filter.

Where to buy

We may earn a commission if you buy through links on this page. It does not change the price you pay.

Shop your printed size and MERV at ordinary merchants. Pack prices move daily — use the dated tables on each size page rather than a number copied here.

Nordic Pure — Factory size pages (pick MERV and pack), e.g. 16x25x1. Published actual sizes are often a slightly smaller cut than Honeywell/Amazon Basics.
Honeywell Store — Current 1-inch High/Ultra Efficiency packs (MERV 11 and MERV 13), e.g. 16x25x1 MERV 11 12-pack.
Filtrete (3M) — Sold widely as MPR grades; many MPR 1000 packs are labeled MERV 11. Search your size at big-box and warehouse merchants, or start from a known size page such as 16x25x1.
Amazon (backup) — Category search for your size, then filter by MERV: furnace filter MERV 13 · 16x25x1 furnace filter.

Affiliate program IDs are not attached yet on every link. Disclosure still applies wherever a merchant link may earn a commission. Full policy: disclosure.

Sources (EPA table accessed 31 Aug 2026).

U.S. EPA, “What is a MERV rating?”: epa.gov/indoor-air-quality-iaq/what-merv-rating (last updated 14 Jan 2026)
ASHRAE Standard 52.2 (the test method EPA summarizes; we cite EPA’s public table, not a paid standard reprint)
Size pages on this site for brand actual sizes and dated pack prices: 16x25x1, 20x20x1, 20x25x1, 16x20x1