NestyFinds

Winix AT40

By the NestyFinds editorial team · Researched from manufacturer documentation, manuals and the AHAM Verifide directory · not bench-tested · Reviewed:

Winix AT40
410 ft² CADR 265 cfm AHAM Verifide CARB certified Filter ~12 mo

AHAM Verifide at 265 cfm smoke across 410 sq ft, and the clearest answer in this catalogue to the ionizer question: CARB calls it Electronic, and two separate laboratories put its ozone emission at essentially nothing.

Pros

  • A full AHAM Verifide set, and Winix publishes the identical 265 cfm rather than a number of its own.
  • It states the air-change basis in its own specification table — 4.8, explicitly tied to the AHAM room size — which almost no brand does.
  • The ionizer question is answered with numbers rather than adjectives: 0.00 ppb in the ENERGY STAR list, and Winix publishes its own 0.12 ppbv measurement with the laboratory report number attached.
  • It ships with two complete filter sets, which Winix puts at up to two years of filtration — an unusual amount of consumable in the box.
  • 22.04 dB at its lowest setting, and Winix publishes the figure to two decimal places rather than rounding to a marketing number.
  • ENERGY STAR certified and, unlike some models here, Winix lists that certification itself — 272 kWh a year at 5.6 cfm per watt.
  • Wi-Fi with both Alexa and Google Home, five speeds, dual sensors and a real auto mode, in a machine weighing ten pounds.

Cons

  • ⚠️ WINIX'S OWN TWO PAGES DISAGREE ABOUT WHICH FILTER THIS MACHINE TAKES. The AT40 product page offers Filter Z (1712-0121-00) as its replacement. Filter Z's own page says it is "Compatible with Winix air cleaner model C610 and C710" and never mentions the AT40. Confirm with Winix before ordering.
  • CARB classifies it Electronic because of PlasmaWave. The measured emissions are essentially nil, but if you want a machine with no ionising stage at all, this is not one, and the pages do not say PlasmaWave can be switched off.
  • Winix publishes no wattage for this model, only ENERGY STAR's annual figure. AHAM recorded 45.0 operating watts.
  • No maximum noise figure is published, only the 22.04 dB minimum. On a five-speed machine that is the half you are less likely to live with.
  • The pollen CADR of 244 is its weakest measured figure, below both its dust and its smoke numbers.
  • A single all-in-one canister means one clock and one part — convenient, but you replace the carbon and the HEPA together whether or not both are spent.

Our editorial rating, not a lab measurement. Weighed independent measurement above manufacturer claims: a full AHAM Verifide set, published identically by the maker, with the air-change basis stated in its own specification table. It is ENERGY STAR certified with the certification acknowledged on its own page, ships with two complete filter sets, and answers the ionizer question with two laboratory figures rather than reassurance. Marked down because Winix's own product page and filter page disagree about which replacement this machine takes, because no wattage or maximum noise level is published, because pollen is its weakest measured figure, and because the PlasmaWave stage cannot be confirmed as switchable.

Verdict

The AT40 is the machine we would point at to settle an argument about ionizers. CARB classifies it Electronic because PlasmaWave is an ionising stage — and then two independent measurements say that stage emits essentially nothing: 0.00 ppb in the ENERGY STAR certified list, and 0.12 ppbv in Winix's own cited laboratory report. Its stablemate the Tower XQ, same technology and same classification, measures 1.00 ppb. The classification tells you a component was found and tested; the number tells you what it actually does. Beyond that it is a well-documented 410 sq ft machine that publishes its air-change basis, ships with two years of filters, weighs ten pounds and carries Wi-Fi with both voice assistants. The one thing to sort out before you buy: Winix's product page offers Filter Z as the replacement, and Filter Z's own page lists compatibility as the C610 and C710 without mentioning this machine at all.

Check current price for the Winix AT40 on Amazon (opens in a new tab)

Price, seller and package contents change. Check the variant on Amazon before you buy.

Is it the right one for you?

Who it's for

  • A living room or large bedroom of roughly 410 sq ft at a genuine 4.8 air changes an hour.
  • Anyone who has been put off by ionizers and would rather read the measurement than the marketing — this is the model in this catalogue where that evidence actually exists.
  • People who want Wi-Fi with both major voice assistants in a machine that weighs ten pounds.
  • Anyone who values getting the first two years of filters in the box.

Who should skip it

  • Anyone who wants no ionising stage at all. CARB classifies this Electronic, and neither page says PlasmaWave can be turned off.
  • Anyone who needs to know the noise level at full speed before buying.
  • Anyone who wants to be certain which replacement filter to order before they own the machine — Winix's two pages currently disagree.
  • Rooms materially larger than 410 sq ft, unless you accept fewer air changes than AHAM's basis.

Specifications

How this coverage figure is stated

4.8 air changes per hour, stated by Winix itself: its specification table has a row reading "Clean Air Changes per Hour (Based on AHAM Verified Room Size) 4.8" next to "AHAM Verified Room Size 410 sq. ft.". AHAM's directory prints the same 410, AHAM's rule gives 265 x 1.55 = 410.75, and the ENERGY STAR record rounds it to 411. Winix also publishes the ladder underneath — 1,968 sq ft in an hour, 984 in 30 minutes, 656 in 20, 492 in 15 — which is the same machine at fewer air changes.

Always compare two purifiers at the same air-change rate; manufacturers pick different ones and the headline square footage is not otherwise comparable.

Winix AT40 — documented specifications
Smoke CADR 265 cfm, AHAM Verifide Winix publishes the same 265
AHAM suggested room size 410 sq ft. Winix states the basis itself: 4.8 clean air changes per hour
CARB Certified, device type Electronic, executive order G-26-150 the classification follows from PlasmaWave
Noise 22.04 dB minimum. Winix publishes no maximum
Power Not published by Winix. AHAM recorded 45.0 operating watts during its smoke test
Replacement filter Filter Z, 1712-0121-00 but see the compatibility warning below
The full record: 10 more documented specifications — nothing is removed, it is just not what decides
Dust CADR 259 cfm, AHAM Verifide
Pollen CADR 244 cfm, AHAM Verifide its weakest measured figure
PM2.5 CADR 261 cfm, AHAM Verifide
Measured ozone emission 0.00 ppb per the ENERGY STAR list 0.12 ppbv 8-hour TWA per Winix's own cited laboratory report
ENERGY STAR Certified V3.0, and Winix lists it among its own certifications. Integrated energy factor 5.6 cfm/W, 272 kWh a year
Dimensions 10.24 x 10.24 x 19 in
Weight 10.2 lb
In the box Two complete 360° all-in-one True HEPA filter sets Winix describes this as up to two years of filtration
Warranty 2 year
Certifications listed by Winix AHAM / Energy Star / UL / CARB / Prop65
9 things we could not verify — we leave these blank rather than estimate them
  • ⚠️ THE AHAM COLUMN ORDER IS DUST FIRST, THEN TOBACCO SMOKE, THEN POLLEN. The printed directory's header reads "Dust CADR | Tobacco Smoke CADR | Pollen CADR | Room Size sq FT", and the live directory labels the same fields explicitly. Reading the first column as smoke would publish the wrong headline figure and a room size that does not reconcile.
  • ⚠️ THE FILTER CONFLICT WAS MEASURED, NOT INFERRED FROM A SUMMARY. On the AT40's page the code 1712-0121-00 appears ten times while every other filter code appears exactly nine — nine being the generic "shop the collection" strip that sits on every Winix page. So Filter Z is designated for this machine, but by a single extra mention. On the Tower XQ's page, by contrast, its Filter X code appears nineteen times against nine, which is what an unambiguous designation looks like. Filter Z's own page names only the C610 and C710.
  • WE DO NOT KNOW WHICH PAGE IS WRONG. Both the AT40 and the C610 are described by Winix as "360° All-in-One" machines, which would be consistent with a shared canister, but Winix does not say so and their AHAM figures differ (265 cfm smoke across 410 sq ft against 248 across 384). We report the conflict rather than picking a side.
  • WHAT A PPB FIGURE MEANS IN CONTEXT. We read the whole ENERGY STAR certified list, 244 models. Of those, 201 are recorded at 0.00 ppb, 23 at 1.00, 13 at 2.00, four at 3.00, and one each at 0.92, 1.35 and 5.00. So a measurable figure is the minority case, and the values that exist are small. We report the number and the distribution; what an individual should do with it is not ours to decide.
  • THE TWO OZONE FIGURES COME FROM DIFFERENT PROTOCOLS. ENERGY STAR's 0.00 ppb and Winix's 0.12 ppbv 8-hour time-weighted average in a 30 m3 chamber are not the same measurement, and we have not seen either method. They are consistent to the precision each publishes; we report both with their sources rather than merging them.
  • WINIX PUBLISHES NO WATTAGE for this model. The 45.0 W is AHAM's measurement during the tobacco-smoke test and the 272 kWh a year is ENERGY STAR's.
  • "TRUE HEPA" AND "99.999%" ARE WINIX'S WORDING from its own specification table. We have not reproduced a filtration grade in our own voice.
  • WHETHER PLASMAWAVE CAN BE SWITCHED OFF IS NOT STATED on the pages we read. Other Winix models in this catalogue have a dedicated button; we are not carrying that across.
  • THE CARB ROW FOR THIS MODEL IS RECENT (executive order G-26-150). Elsewhere in this catalogue the device class has changed between revisions of the same model name, so a class describes a certified revision rather than a model name forever.

Our calculation, not the manufacturer’s

What 265 cfm of smoke CADR actually covers

Air changesWhen you want this rateRoom it suits
4.8×/hourWildfire smoke, allergy season, a room you are sensitive in414 ft²
4×/hourThe rate most allergy guidance assumes497 ft²
2×/hourGeneral freshening in a room without a specific problem994 ft²

Worked from the CDC/NIOSH relation air changes = (CADR × 60) ÷ (area × ceiling height), assuming an 8 ft ceiling. Change the ceiling height and these numbers change. AHAM’s own consumer rule — a smoke CADR of at least two-thirds of the room’s area — puts the ceiling for this unit at about 398 ft², which is the same arithmetic at roughly five air changes an hour.

You can check this at home. In a closed room of the size in the first row, PM2.5 should halve about every nine minutes at top speed once its source stops. A monitor shows whether this unit manages that in your home. How to run the test

Ionizer and ozone

THIS IS THE BEST-EVIDENCED ANSWER TO THE IONIZER QUESTION IN THIS WHOLE CATALOGUE, AND IT IS WORTH READING IN FULL.

CARB's complete list carries "Winix | Air Purifier | AT40 | Electronic | ... | G-26-150", with the AT41 under the same order. Electronic means California's certifier identified a component capable of producing ozone — here, PlasmaWave — and therefore TESTED the machine against the state's emission limit, which it passed. Nearly every Winix model on CARB's list is classified this way; of the thirty-three distinct Winix models we counted, only the WX101 is Mechanical.

So what does that classification actually cost you on this machine? Two independent measurements say: essentially nothing.

· The ENERGY STAR certified-products list records this model's ozone emission as 0.00 ppb. · Winix publishes its own figure on the product page, with the report number attached: "The 8-hr TWA Ozone for this product is 0.12 ppbv when tested in a 30 m3 chamber", citing a KCL independent report (CT26-043210K) under SPS-KACA 002-0132:2022 Modified.

Those two are consistent rather than contradictory: 0.12 ppbv rounds to 0.00 at the two decimal places ENERGY STAR publishes. Different protocols, same conclusion.

The lesson generalises, and it is why this page spends words on it: CARB Electronic tells you a component was found and tested, NOT that the machine emits anything you could measure. Winix's own Tower XQ, same PlasmaWave technology, same Electronic class, is recorded at 1.00 ppb. The classification is about the design; the number is about the machine.

Whether PlasmaWave can be switched off is not stated on the pages we read.

What you actually get

What the linked package includes
Capability What it needs Status
Particle filtration 360° all-in-one True HEPA canister — two complete sets in the box Included
Odour reduction Activated carbon, part of the same canister Included
Wi-Fi, app and voice control Winix Smart App; Alexa or Google Home account Included
Auto mode with sensors Dual smart sensors, built in Included
Spare filter set A second set ships in the box Included
Replacement canister after that Filter Z (1712-0121-00) per the product page — confirm first, see the warning Sold separately
Switching PlasmaWave off Not stated on the pages we read Not verified
Published maximum noise level Winix publishes only the 22.04 dB minimum Not verified

Package contents vary by variant and seller. Check what is in the box on the Amazon listing before you buy. “Not verified” means the manufacturer does not document it either way — not that it is missing. “Not offered” is the other thing: the manufacturer does document it, and the answer is that this model does not have it.

Replacement filter

Full filter guide

Winix Filter Z all-in-one canister

Part 1712-0121-00 · Twelve months. Winix's wording: "Genuine Winix one year replacement filter set. For optimal performance, it is recommended to change the All-in-one True HEPA Canister Filter once every 12 months." One canister, one clock. Worth noting against machines in this catalogue that run a HEPA stage annually and a pre-filter quarterly: this design asks you to remember one date, not two.

Which filter fits

How we researched this

Checked against the AHAM Verifide directory, CARB's certified air-cleaner list, the ENERGY STAR certified-products list and the manufacturer's own pages. We did not test this unit. Nothing here is a measurement of ours: every figure is either documented by the manufacturer or published by an independent standards or testing body, and where the two disagree this page says so.

Not verified for this model — 9 notes
  • ⚠️ THE AHAM COLUMN ORDER IS DUST FIRST, THEN TOBACCO SMOKE, THEN POLLEN. The printed directory's header reads "Dust CADR | Tobacco Smoke CADR | Pollen CADR | Room Size sq FT", and the live directory labels the same fields explicitly. Reading the first column as smoke would publish the wrong headline figure and a room size that does not reconcile.
  • ⚠️ THE FILTER CONFLICT WAS MEASURED, NOT INFERRED FROM A SUMMARY. On the AT40's page the code 1712-0121-00 appears ten times while every other filter code appears exactly nine — nine being the generic "shop the collection" strip that sits on every Winix page. So Filter Z is designated for this machine, but by a single extra mention. On the Tower XQ's page, by contrast, its Filter X code appears nineteen times against nine, which is what an unambiguous designation looks like. Filter Z's own page names only the C610 and C710.
  • WE DO NOT KNOW WHICH PAGE IS WRONG. Both the AT40 and the C610 are described by Winix as "360° All-in-One" machines, which would be consistent with a shared canister, but Winix does not say so and their AHAM figures differ (265 cfm smoke across 410 sq ft against 248 across 384). We report the conflict rather than picking a side.
  • WHAT A PPB FIGURE MEANS IN CONTEXT. We read the whole ENERGY STAR certified list, 244 models. Of those, 201 are recorded at 0.00 ppb, 23 at 1.00, 13 at 2.00, four at 3.00, and one each at 0.92, 1.35 and 5.00. So a measurable figure is the minority case, and the values that exist are small. We report the number and the distribution; what an individual should do with it is not ours to decide.
  • THE TWO OZONE FIGURES COME FROM DIFFERENT PROTOCOLS. ENERGY STAR's 0.00 ppb and Winix's 0.12 ppbv 8-hour time-weighted average in a 30 m3 chamber are not the same measurement, and we have not seen either method. They are consistent to the precision each publishes; we report both with their sources rather than merging them.
  • WINIX PUBLISHES NO WATTAGE for this model. The 45.0 W is AHAM's measurement during the tobacco-smoke test and the 272 kWh a year is ENERGY STAR's.
  • "TRUE HEPA" AND "99.999%" ARE WINIX'S WORDING from its own specification table. We have not reproduced a filtration grade in our own voice.
  • WHETHER PLASMAWAVE CAN BE SWITCHED OFF IS NOT STATED on the pages we read. Other Winix models in this catalogue have a dedicated button; we are not carrying that across.
  • THE CARB ROW FOR THIS MODEL IS RECENT (executive order G-26-150). Elsewhere in this catalogue the device class has changed between revisions of the same model name, so a class describes a certified revision rather than a model name forever.

Sources consulted

Other purifiers we have researched

All reviews