Winix AT40
Room air purifier · suggested up to 410 sq ft · True HEPA (H13) + activated carbon
Buy the Winix AT40 on Amazon — $192.57 →This exact model.
A room air purifier rated to clear 265 CFM of smoke-sized particles — enough for a room up to about 410 sq ft.
Buy this purifier
$192.57 at Amazon
Winix AT40 room air purifier
Check current price →Links to the exact listing; price was current at our last data refresh and can change at Amazon.
All 25 certified Winix models compared, with prices →
At a glance
Who it's for
Large living rooms and open-plan spaces that need real air-cleaning power.
The standout number
Smoke CADR of 265 — the number that decides how fast it clears wildfire smoke and fine particles.
The catch
The carbon filter that handles odors and gases wears out faster than the HEPA — budget for replacements.
What size room does the Winix AT40 cover?
AHAM certifies it for rooms up to 410 sq ft. In a room that size it cleans the air about 4.8 times an hour on its top speed (our math: 265 smoke CADR x 60 / the room volume, with 8-foot ceilings). In a room half that size (205 sq ft) it would clean the air about 9.7 times an hour.
How much does the Winix AT40 filter cost, and how often do you change it?
The maker says: “360 All-in-One True HEPA Filter ... Lasts Approx. 12 months; Intervals between filter replacement may vary depending on environment.” The matching genuine filter (360 All-in-One True HEPA Filter) is $49.99 on Amazon. Changed every 12 months, that is about $50 a year. Maker source.
How do you reset the filter light on the Winix AT40?
The maker's manual says: “Resetting Filter Life: After replacing the 360° All-in-One True HEPA Filter, while the unit is on, hold the Filter Reset Button for at least 5 seconds until you hear the beep. After the beep, the red blinking Filter Replacement Indicator will turn off.” Maker source: AT40 / AT41 User Manual.
The Verified Label — every AHAM-tested spec
ENERGY STAR listed
US market
Clean Air Delivery Rate (CADR) — source: AHAM
Coverage & power — source: AHAM (+ computed)
Filter & identity
How it ranks
Where this unit sits among the 236 room air purifiers we track, on the two numbers that decide one: how fast it clears fine smoke particles, and how big a room it covers. A higher percentile is better.
Smoke CADR
Better than 82%
of the 236 units with a published smoke CADR
Suggested room size
Better than 82%
of the 236 units with a published room size
Compare similar air purifiers
Frequently asked questions
How big a room does the Winix AT40 cover?
AHAM suggests it for a room up to 410 square feet. That rating assumes it runs on high and cleans the air about 4.8 times an hour. For faster cleaning — say for wildfire smoke or allergies — size it to a smaller room than the maximum.
What is the CADR of the Winix AT40?
Its AHAM Clean Air Delivery Rate is 259 for dust, 265 for smoke and 244 for pollen, with a PM2.5 CADR of 261. CADR is cubic feet of clean air delivered per minute — higher clears a room faster.
Does the Winix AT40 use a real HEPA filter?
Its filter is listed as True HEPA (H13) + activated carbon. True HEPA captures 99.97% of particles down to 0.3 microns. The activated-carbon layer also helps with odors and gases.
How much power does the Winix AT40 use?
About 45 watts on its smoke-clearing setting, which works out to 5.9 CADR per watt — a measure of how much clean air you get for the electricity it draws. It is ENERGY STAR certified.
Where can I buy the Winix AT40?
It's a retail unit — we matched its Amazon listing, linked on this page, so you can check the current price and seller. The replacement filters are the recurring cost — check those before you commit to a brand.
Sources. Clean Air Delivery Rate (dust / smoke / pollen), PM2.5 CADR, suggested room size, ENERGY STAR status and power draw come from the AHAM Verifide air-cleaner directory (the industry's independent CADR test). Average CADR, clean-air-per-watt and the percentile figures are computed by Verified HVAC Data from those published ratings. We publish no star ratings and take no payment for placement. "Not published" means AHAM's record doesn't disclose it — we never fill a spec with a guess.
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