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Winix AT40 quick verdict: easy clean air for a mid-size room
The Winix AT40 is a simple, smart air purifier for bedrooms and living rooms up to about 410 sq ft. It combines a True HEPA filter with activated carbon, adjusts itself in Auto Mode and connects to the Winix Smart App. The Amazon bundle we link to is sold with two years of filters, so your first replacement is already in the box.
Why buyers like it: a tidy round design that pulls in air from every side, a color light that shows air quality at a glance, a 22 dB quietest setting and Alexa or Google Home voice control.
Know before you buy: the 1,968 sq ft headline means one air change per hour, not a deep clean of a huge space. The sensor shows Good, Fair or Poor rather than a PM2.5 number, and Winix does not publish the maximum noise level.
TRUE HEPA AIR PURIFIER · AMAZON AFFILIATE LINK
Winix AT40 with 2 years of filters
White 4-stage purifier with Wi-Fi, Auto Mode and two 360° True HEPA filter sets.
Prices and bundles change. Confirm the listing shows the Winix AT40 with two filter sets, plus the seller and return terms.
Winix AT40 specs at a glance
| Specification | Winix rating | What it means for you |
|---|---|---|
| Model | Winix AT40 (AT41 is listed as the same certified model) | Check the model number on the listing. |
| Clean air delivery rate (CADR) | 265 smoke / 259 dust / 244 pollen CFM | Strong airflow for a mid-size room. |
| PM2.5 CADR | 261 CFM (ENERGY STAR) | Fine-particle cleaning matches the headline CADR. |
| Recommended room size | 410 sq ft at 4.8 air changes per hour (AHAM Verified) | The best number to use for a bedroom or allergy room. |
| Maximum coverage | 1,968 sq ft at one air change per hour; 984 sq ft in 30 minutes | Light background cleaning in a big space. |
| Filtration | 4 stages: fine-mesh pre-filter, True HEPA, activated carbon, PlasmaWave | Pre-filter, HEPA and carbon sit in one 360° filter. |
| Filter life and part | About 12 months; Winix Filter Z (1712-0121-00), $59.99 at Winix | This bundle includes two filter sets. |
| Fan speeds and modes | 5 fan speeds; Auto Mode, Sleep Mode with light sensor | Set it and let the sensor adjust the fan. |
| Air-quality display | 3-color LED (blue, amber, red) plus GOOD / FAIR / POOR text | A quick-glance rating, not a PM2.5 number. |
| Noise | From 22 dB on the quietest setting | Winix does not publish the maximum noise level. |
| Power | 45 W rated; 120 V / 60 Hz | For US and Canadian outlets only. |
| Energy use | ENERGY STAR certified; 5.6 CFM per watt; 272 kWh per year (ENERGY STAR estimate) | Low running cost for its size. |
| Ozone | 0.0 ppb (ENERGY STAR); CARB certified | PlasmaWave can also be switched off. |
| Controls | Child Lock, 4 display brightness levels (down to off), filter-life % on demand | Handy in bedrooms and homes with kids. |
| Smart features | Wi-Fi, Winix Smart App (remote control, timer, alerts), Alexa, Google Home | Control it from your phone or by voice. |
| Size and weight | About 10.5 × 10.5 × 19 in; 10.2 lb | Small enough for a nightstand corner or beside a sofa. |
| Placement | 12–18 in from walls and electronics | Leave space around it for full airflow. |
| In the box | Purifier, two 360° True HEPA filters, user manual, Wi-Fi setup guide | Confirm the bundle on the Amazon listing. |
| Warranty | 2-year limited warranty (USA and Canada) | Keep your proof of purchase. |
Ratings from Winix’s AT40 product page, its user manual and the ENERGY STAR certification record—not Decively measurements. The manual lists 10.45 × 10.45 × 19.03 in; the product page lists 10.24 × 10.24 × 19 in. On a phone, swipe the table sideways.
How big a room can the Winix AT40 really clean?
CADR tells you how much clean air a purifier delivers. With a smoke CADR of 265, the AT40 is rated for a 410 sq ft room at 4.8 air changes per hour. That means it can cycle the air in a room that size almost five times an hour—a good target if allergies are why you are buying.
The 1,968 sq ft figure means one air change per hour (Winix also lists 984 sq ft in 30 minutes). Those bigger numbers suit light background filtering in open-plan spaces, not an allergy bedroom.
Quick sizing tip: multiply length by width. A 14 × 16 ft bedroom is 224 sq ft, well inside the 410 sq ft rating, so the AT40 can run on a lower, quieter speed and still keep up.
Winix AT40 in a living room (manufacturer image).
Winix AT40 filters and replacement cost
Everything sits in one round 360° filter: a fine-mesh pre-filter, a True HEPA layer and activated carbon. Winix rates the HEPA layer at 99.999% particle capture, and the carbon helps with everyday odors such as cooking smells. Air enters from all sides; just leave 12–18 inches of space around it.
Care is simple. Vacuum or brush the pre-filter about every 14 days, and replace the whole filter roughly every 12 months, or when the red Check Filter light blinks. The filter is not washable.
Filter cost: Winix sells the replacement Filter Z (1712-0121-00) for $59.99 on its own store (checked November 4, 2026). Because this bundle includes two filter sets, you may not need to buy one for about two years.
PlasmaWave is an extra electronic cleaning stage with its own button, so you can switch it off at any time. The AT40 is CARB certified, and its ENERGY STAR record lists ozone emissions of 0.0 ppb.
Smart sensor, app and voice control
A built-in smart sensor checks the air and lights a color bar: blue for Good, amber for Fair and red for Poor. The display also spells out GOOD, FAIR or POOR. In Auto Mode, the fan speeds up when the air gets worse and slows down when it clears.
Control panel showing a GOOD air-quality reading (manufacturer image).
A light sensor switches to Sleep Mode when the room goes dark, and you can dim the display in steps down to fully off. Child Lock keeps small hands away from the buttons.
On Wi-Fi, the Winix Smart App lets you check air quality, change modes and set a timer from your phone. The AT40 also works with Amazon Alexa and Google Home.
One limit: Winix does not say exactly what the sensor measures, and you get a three-level rating, not a PM2.5 number. Treat it as a guide for the fan, not a lab instrument.
Is the Winix AT40 quiet and cheap to run?
Winix rates the quietest setting at 22 dB—quieter than a typical whisper, which suits sleep. Turbo is louder, and Winix does not publish that figure, so expect more fan noise when you want the fastest cleaning.
Power is rated at 45 W, and the AT40 is ENERGY STAR certified. ENERGY STAR estimates 272 kWh a year—roughly $46 at an example rate of 17¢ per kWh. Your bill depends on the speeds and hours you use.
Who should buy the Winix AT40?
Buy it if you want one purifier for a bedroom, home office or living room up to about 410 sq ft; you deal with dust, pollen, pet dander or smoke; and you like to set it to Auto and forget it. The two included filter sets make the first two years easy to budget.
Skip it if you need allergy-level cleaning in a large open-plan space, want a live PM2.5 number on screen or need humidity control. A purifier does not replace regular cleaning; our guide to air purifiers and dust explains what helps most. Comparing quiet options? See our best air purifiers for bedrooms.
READY TO BUY · AMAZON AFFILIATE LINK
Winix AT40 True HEPA Air Purifier
Sold with two years of filters. Confirm the seller, current price and return terms on Amazon.
Winix AT40 FAQ
Is the Winix AT40 a Xiaomi air purifier?
No. The AT40 is made by Winix, an air purifier brand from South Korea. It can appear in searches for Xiaomi purifiers, but it uses Winix’s own app and filters.
Does the Winix AT40 come with filters?
Yes. The manual lists two 360° True HEPA filters in the box, each lasting about 12 months. Replacements are Winix Filter Z (1712-0121-00).
Can you turn off PlasmaWave?
Yes. The control panel has a PlasmaWave button that switches it on or off.
How much electricity does the Winix AT40 use?
It is rated at 45 W. ENERGY STAR estimates 272 kWh a year, about $46 at 17¢ per kWh.
Is the Winix AT40 good for a bedroom?
For most bedrooms, yes. It starts at 22 dB, switches to Sleep Mode in the dark, lets you turn the display off, and a typical bedroom is well under its 410 sq ft rating.
Research notes
Research checked November 5, 2026, using Winix’s AT40 product page, the AT40/AT41 user manual and the ENERGY STAR record. Decively has not tested this purifier; all figures are manufacturer or ENERGY STAR ratings. We could not review every detail of the Amazon listing, so confirm the bundle contents, seller and price there. Images are Winix manufacturer images.
