Coway Airmega 450 Review
Coway's large-room machine, read against the register rather than the box. We do not test units; this is what the record shows and what Coway leaves out.
#ad We earn a commission if you buy through this link, at no extra cost to you. How this site is funded. Prices last checked September 23, 2026.
A large-room machine with an unusually complete record: 443 certified smoke CADR across 687 certified square feet, 0.00 ppb measured ozone, no ion stage, a HEPA-Type filter classification, a vacuumable pre-filter and three filter compositions to choose from. The two blanks: no replacement filter price, and a published top speed of 57.7 dB(A).
First, the disclosure: we have not tested this unit. We own no air purifiers and run no laboratory. What follows is the ENERGY STAR record plus Coway’s own published specification, each labeled — our method, including where it runs out.
The certified record
| Specification | Figure | Source |
|---|---|---|
| Smoke CADR | 443 CFM | ENERGY STAR |
| Dust CADR | 445 CFM | ENERGY STAR |
| Pollen CADR | 450 CFM | ENERGY STAR |
| PM2.5 CADR | 444 CFM | ENERGY STAR |
| Certified room size | 687 sq ft | ENERGY STAR, at 4.8 ACH |
| Two-thirds-rule room | 664 sq ft | Our arithmetic on the CADR |
| Annual energy use | 389 kWh | ENERGY STAR |
| Electricity per year | $71 | Our arithmetic at a named rate |
| Air per watt | 6.7 CFM/W | ENERGY STAR |
| Measured ozone | 0.00 ppb | ENERGY STAR |
| Technology | Fan and Filter | ENERGY STAR |
| Filter classification | HEPA-Type | ENERGY STAR |
| Power draw | 72 W | Coway |
| Noise | 23.6-57.7 dB(A) | Coway |
| Pre-filter | Vacuumable | Coway |
| Filter set | 3-in-1 custom set, 1 year or more, three compositions | Coway |
| Replacement filter price | Not published in our sources | — |
| Size and weight | 13 in square, 29 in tall, 24.9 lb | Coway |
Electricity costs on this page use 18.34¢ per kWh, the U.S. average residential price for June 2026 from the U.S. Energy Information Administration, Electric Power Monthly, Table 5.3. Your rate is on your bill and is probably not this one; multiply the kWh figure by your own rate and you have your number.
What it is genuinely good at
Certified coverage with a measured zero. Machines certified past 600 square feet are a short list, and the ones that also measure 0.00 ppb with no ion stage are shorter: this, the LEVOIT Core 600S and the Airmega ProX. For an open-plan floor in a household with asthma, that list is the whole decision — the large-room roundup ranks all of them.
It is the efficient one in its own family. The 450 moves 18% more certified air than the Airmega 400 for 6% more certified energy, which is not how a size step usually goes. The register rates it 6.7 CFM per watt against the 400’s 6.1.
A choice of filter composition. Coway sells the 3-in-1 set in three versions — a standard starter, an allergen-focused set and one aimed at smoke. Most manufacturers sell one cartridge and expect it to suit every household; being able to pick the carbon-heavy version for a smoky or pet-heavy home is a genuine advantage.
A pre-filter you maintain rather than replace. Coway describes the pre-filter as vacuumable. In a home with a shedding animal the pre-filter is what protects the expensive cartridge — the units that document one are a short list.
Where it is beaten, and what is missing
Noise at the top of the range. 57.7 dB(A) is the loudest high end we print for any machine on this site. That is the speed the unit needs to deliver its certified figure, and in a room where people are talking it is audible. Coway publishes no CADR per fan speed, so there is no way to work out what you give up by running it lower — how to read a dB range.
No filter price. Coway publishes a price for the Airmega 400’s Max2 set but none we could source for the 450’s 3-in-1 set, so the running-cost arithmetic that can be completed for the smaller machine cannot be completed for this one. The interval is published — a year or more — which is half of what you need.
Efficiency, in absolute terms. 6.7 CFM per watt is mid-table. The Airmega ProX manages 10.2 and the Blueair 211i Max 9.0, both while covering more room, so the 450 is the efficient Coway rather than an efficient machine.
A tall footprint. 29 inches on a 13-inch-square base is narrower than the Airmega 400 but half a foot taller, which matters if it is going beside furniture rather than in a corner.
The room it actually fits
| Room | ACH | Verdict |
|---|---|---|
| 400 sq ft | 8.3 ACH | More machine than the room needs |
| 553 sq ft | 6.0 ACH | Our 6 ACH pet-room target, exactly |
| 664 sq ft | 5.0 ACH | AHAM's two-thirds rule, exactly |
| 687 sq ft | 4.8 ACH | The register's own figure |
| 800 sq ft | 4.2 ACH | Too big — that is the ProX |
Who should buy it
Buy it for an open-plan floor between about 564 and 664 square feet where you want certified coverage, a measured zero and a pre-filter you can maintain, and where the machine will usually run at a middle speed.
Buy something else if the room is smaller — the Airmega 400 covers 583 square feet and its whole running cost is publishable — or larger, where the ProX certifies 894 square feet on less electricity than this.
Choosing between its three filter sets
Coway sells the 450’s 3-in-1 cartridge in three compositions, which is unusual and genuinely useful: a standard starter set, an allergen-focused set and one aimed at smoke. The machine and its certified figures are the same in each case — CADR is measured on the unit as tested — so this is a choice about which contaminant the carbon and media are weighted toward, not about airflow.
The practical guidance is the same as for any carbon machine. If the complaint is a smell — cooking, smoke, a litter box — the carbon-heavier option earns its money and will need replacing sooner than a particle-only filter would. If the complaint is dander or pollen, the standard set is the one to buy, and the money is better spent on vacuuming the pre-filter often enough that the cartridge lasts its full year.
Quick picks
The 450 against the machines either side of it in Coway's own range.
| # | Product | Best for | Certified CADR | Price |
|---|---|---|---|---|
| 1 |  The unit reviewed Coway Airmega 450 443 certified CFM across 687 sq ft, 0.00 ppb, vacuumable pre-filter. | Open-plan floors up to about 665 sq ft | 443CFM smoke ENERGY STAR verified | |
| 2 |  If the room is smaller Coway Airmega 400 376 certified CFM, and the only machine here with a publishable filter bill. | Large rooms, verified Coway | 376CFM smoke ENERGY STAR verified | |
| 3 |  If the room is bigger Coway Airmega ProX 577 certified CFM across 894 sq ft on less electricity than the 450. | The largest room one machine can certifiably cover | 577CFM smoke ENERGY STAR verified |
#ad We earn a commission if you buy through this link, at no extra cost to you. How this site is funded. Prices last checked September 23, 2026.
The alternatives worth weighing
Coway Airmega 400
Coway · model Airmega 400 (AP-2015F)
#ad We earn a commission if you buy through this link, at no extra cost to you. How this site is funded. Prices last checked September 23, 2026.
The Coway that is actually in a certification register: 376 certified smoke CADR, 583 square feet, zero measured ozone. If you want a Coway, this is the one with third-party numbers.
376 smoke / 384 dust / 409 pollen CFM · 380 PM2.5
- Certified room size
- 583 sq ft
- Advertised coverage
- 3,120 sq ft in 60 minutes
- Energy / year
- 366 kWh
- Electricity / year
- $67
- Air per watt
- 6.1 CFM/W
- Power draw
- 66 W
- Noise
- 22-52 dB(A)
- Measured ozone
- 0 ppb
- Filter class
- Composite Filter
- AHAM rule, 500 sq ft
- Clears it (334 needed)
No ionizer — filtration only
ENERGY STAR classifies this unit 'Fan and Filter', 0.00 ppb measured ozone.
376 certified smoke CADR across 583 certified square feet, 0.00 ppb, washable pre-filters on both faces — and the only machine we cover whose whole annual running cost is publishable, because Coway lists both a filter price and an interval. Our full review.
The honest con: ENERGY STAR declines to classify its filter HEPA or HEPA-Type at all, it is less efficient than the 450, and its filters cost more per year than its electricity.
Coway Airmega ProX
Coway · model Airmega ProX (AP-3522F)
#ad We earn a commission if you buy through this link, at no extra cost to you. How this site is funded. Prices last checked September 23, 2026.
The largest certified coverage on this site at 894 square feet, and the highest air-per-watt figure we have recorded at 10.2 CFM per watt — with a measured zero on ozone.
577 smoke / 586 dust / 450 pollen CFM · 581 PM2.5
- Certified room size
- 894 sq ft
- Advertised coverage
- 4,253 sq ft in 60 minutes
- Energy / year
- 335 kWh
- Electricity / year
- $61
- Air per watt
- 10.2 CFM/W
- Power draw
- 65 W
- Noise
- 23-46 dB(A)
- Measured ozone
- 0 ppb
- Filter class
- HEPA-Type
- AHAM rule, 800 sq ft
- Clears it (534 needed)
No ionizer — filtration only
ENERGY STAR classifies this unit 'Fan and Filter' and measures 0.00 ppb ozone. Coway's specification lists no ionizing stage.
577 certified smoke CADR across 894 certified square feet at 10.2 CFM per watt — the largest coverage and the best efficiency figure on this site, on 335 kWh a year, which is less electricity than the 450 uses for less room.
The honest con: a considerably higher price bracket, and in a room under 664 square feet its extra capacity is headroom you pay for without using.
Common questions
Is the Coway Airmega 450 worth it?
What size room is the Airmega 450 for?
Is the Airmega 450 better than the Airmega 400?
How loud is the Coway Airmega 450?
Sources
- ENERGY STAR certified room air cleaners database
- AHAM — air filtration standards and the two-thirds rule
- Coway Airmega 450 specification
- EPA — Guide to Air Cleaners in the Home
Figures were read on the dates shown against each source. If one has changed, or if we have got something wrong, tell us and we will correct the page.
Read next
- Room sizeCoway Airmega 400 vs Airmega 450443 certified CFM against 376 on only 6% more energy, plus a HEPA-Type classification the 400 lacks. Under 564 sq ft, the 400 is still enough.
- Room sizeThe Best Air Purifiers for Large RoomsCertified for 500+ square feet, ranked on real coverage and what each costs to run.
- Room sizeThe Best Air Purifiers for 1,000 Square FeetNo certified single unit covers 1,000 sq ft. The Coway Airmega ProX reaches about 865; past that the answer is two machines in two zones.