Coway vs. Dyson vs. Blueair vs. Levoit: We Tested 9 Air Purifiers and Found a Clear Winner
We measured PM2.5 reduction, noise, and CADR across identical rooms. The results weren't close.
By Marcus Chen
Reviewed by HSH Editorial
Updated May 28, 2026
9 min read
Affiliate disclosure: HomeSweetHacks is reader-supported. We may earn a commission on purchases — we never accept payment for reviews. See our methodology.
We screened 9+ home air quality products and narrowed it to 4 finalists: Coway Airmega 400S, Dyson Purifier Cool Formaldehyde, Blueair Blue Pure 311i+, Levoit Core 400S. With Marcus Chen, we ranked them on cleaning, noise, filter, app, price.
1.Top Home Air Quality, Compared
Coway Airmega 400SWinnerTap ▾Hide ▴
- Best For
- Best Overall
- CADR (Smoke)
- 350
- Room Size (sq ft)
- 1,560
- Noise at Low (dB)
- 24
- HEPA Grade
- True HEPA
- Filter Life (months)
- 12
- Annual Filter Cost
- $70
- Price
- $469
Dyson Purifier Cool FormaldehydeTap ▾Hide ▴
- Best For
- Design + Tech
- CADR (Smoke)
- 240
- Room Size (sq ft)
- 800
- Noise at Low (dB)
- 30
- HEPA Grade
- HEPA 13
- Filter Life (months)
- 12
- Annual Filter Cost
- $160
- Price
- $749
Blueair Blue Pure 311i+Tap ▾Hide ▴
- Best For
- Mid-Sized
- CADR (Smoke)
- 250
- Room Size (sq ft)
- 388
- Noise at Low (dB)
- 28
- HEPA Grade
- HEPASilent
- Filter Life (months)
- 9
- Annual Filter Cost
- $110
- Price
- $300
Levoit Core 400STap ▾Hide ▴
- Best For
- Budget
- CADR (Smoke)
- 260
- Room Size (sq ft)
- 1,980
- Noise at Low (dB)
- 26
- HEPA Grade
- True HEPA
- Filter Life (months)
- 8
- Annual Filter Cost
- $85
- Price
- $220
| Coway Airmega 400S★ | Dyson Purifier Cool Formaldehyde | Blueair Blue Pure 311i+ | Levoit Core 400S | |
|---|---|---|---|---|
| Best For | Best Overall | Design + Tech | Mid-Sized | Budget |
| CADR (Smoke) | 350 | 240 | 250 | 260 |
| Room Size (sq ft) | 1,560 | 800 | 388 | 1,980 |
| Noise at Low (dB) | 24 | 30 | 28 | 26 |
| HEPA Grade | True HEPA | HEPA 13 | HEPASilent | True HEPA |
| Filter Life (months) | 12 | 12 | 9 | 8 |
| Annual Filter Cost | $70 | $160 | $110 | $85 |
| Price | $469 | $749 | $300 | $220 |
2.Scorecards
Each finalist scored 1–10 across five weighted criteria. Overall = Cleaning 40% + Noise 25% + Filter 15% + App 10% + Price 10%.
Coway Airmega 400S
Editor's PickCleaning
9.7
40%
Noise
9.4
25%
Filter
9.0
15%
App
8.5
10%
Price
8.0
10%
The performance-per-dollar champion. Highest CADR in the test, lowest noise on auto, and the only finalist with a 5-year warranty.
Pros
- Fastest PM2.5 drop in test
- Whisper-quiet on auto
- 5-year warranty
Cons
- Bulky footprint
- Plastic finish looks generic
Dyson Purifier Cool Formaldehyde
Cleaning
8.4
40%
Noise
7.0
25%
Filter
7.5
15%
App
9.6
10%
Price
5.5
10%
Beautiful, smart, and uniquely good at formaldehyde — but 3x the filter cost and noticeably louder.
Pros
- Best app + display in category
- Doubles as a fan
- Catalyzes formaldehyde
Cons
- $160/yr filters
- Louder than every competitor
- Most expensive
Blueair Blue Pure 311i+
Cleaning
8.2
40%
Noise
9.2
25%
Filter
8.5
15%
App
8.0
10%
Price
8.5
10%
Best small-room purifier. HEPASilent tech is genuinely quiet; coverage tops out at 388 sq ft.
Pros
- Quietest on high speed
- Beautiful fabric pre-filter
- Compact
Cons
- Limited to ~400 sq ft
- Pre-filter wears in 6 months
Levoit Core 400S
Cleaning
8.5
40%
Noise
9.0
25%
Filter
7.8
15%
App
8.8
10%
Price
9.5
10%
The budget pick. Cleans well for the price and the app actually works; loses on long-term filter cost.
Pros
- Cheapest in the test
- Strong app + auto mode
- Good for living-room sizes
Cons
- Filters need replacement every 8 months
- Loud on top setting
3.Cleaning Effectiveness: Coway Hits 4 In 18 Minutes
Identical 350 sq ft sealed living room. PM2.5 baseline established with a calibrated incense burn to 85 µg/m³. Each purifier ran on auto for 30 minutes; PM2.5 logged every 5 minutes with an IQAir AirVisual Pro. Time to 5 µg/m³: Coway 18 min, Levoit 26 min, Blueair 31 min, Dyson 34 min. The Coway hit 4 µg/m³ at minute 22.
"The Coway dropped the PM2.5 reading from 85 to 4 in under 20 minutes. Every other purifier took twice as long."
4.Noise: All Four Pass Low, Coway Wins High
Decibel meter at 3 feet, every fan setting. At low: all four under 31 dB (whisper). At medium: Coway 38, Blueair 39, Levoit 42, Dyson 47. At max: Coway 54, Blueair 56, Levoit 62, Dyson 65 (audible from the next room). For bedrooms, only Coway and Blueair are usable on medium during sleep.
5.Filter Cost: Coway $70/yr vs. Dyson $160/yr
Annual replacement cost at the manufacturer's recommended schedule and current MSRP: Coway $70, Levoit $85, Blueair $110, Dyson $160. Over a 5-year lifespan that's a $450 swing — more than the difference in purchase price between any two units.
6.Price: 5-Year Total Cost Of Ownership
5-year TCO (purchase + filters): Coway $819, Levoit $645, Blueair $850, Dyson $1,549. The Levoit is cheapest if you have a small space; the Coway is cheapest per CADR point across any room over 400 sq ft.
7.The Winner: Coway Airmega 400S
After 50+ hours across 9 purifiers, the Coway Airmega 400S is the clear winner. It cleared rooms fastest, ran quietest on auto, and is the cheapest premium unit to own over five years. The Dyson is genuinely beautiful and uniquely good at formaldehyde — but you're paying triple for filters. The Blueair 311i+ is the right pick for rooms under 400 sq ft.
"I've tested every flagship purifier of the last five years. The Coway 400S is the first one I'd recommend without caveats."
Ready to try Coway Airmega 400S? See today's price.