Head to head
Coway Airmega 400 vs Dyson Purifier Hot+Cool Formaldehyde HP09
Coway Airmega 400 leads 4 to 1 on the 5 rankable specs and costs $250 less, which makes it the straightforward pick.
Catalog as of September 1, 2026
Why, in numbers
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Compare a different air purifier
Levoit Core 300S Smart True HEPA Air Purifier$149Winix 5500-2 Air Purifier$159Levoit Core 400S$219Coway Airmega AP-1512HH Mighty$229Blueair Blue Pure 311i Max$229Honeywell HPA300 HEPA Air Purifier$249Levoit Core 600S Smart True HEPA$299Blueair Blue Pure 211+ Auto$339Coway Airmega 250$399Blueair Protect 7470i$649Alen BreatheSmart 75i Large Room Air Purifier$749Buying for
Straight answer
Overall: 4 to 1
Buy the Coway Airmega 400.
- Leads 4 of 5 rankable overall specs; Dyson Purifier Hot+Cool Formaldehyde HP09 takes 1.
- CADR: 350 CFM vs 190 CFM class
- Coverage area: 1,560 sq ft vs 500 sq ft room size with 350° oscillation
- It is also $250 cheaper.
Deal-breakers
tick what would make you walk away
- Trips:Coway Airmega 400 · Smart Auto Mode + Eco ModeClear:Dyson Purifier Hot+Cool Formaldehyde HP09 · MyDyson App, voice control via Alexa, G…
- Clear:Coway Airmega 400 · 22 dB (Sleep mode) – 52 dB (Max speed)Trips:Dyson Purifier Hot+Cool Formaldehyde HP09 · 46 dB (Low) – 62 dB (Max)
- Clear:Coway Airmega 400 · 1,560 sq ftTrips:Dyson Purifier Hot+Cool Formaldehyde HP09 · 500 sq ft room size with 350° oscillati…
At a glance
The handful of numbers that decide most purchases in this category.
CADR
Coway
350 CFM (Smoke), 328 CFM (Dust), 400 CFM (Pollen)
Dyson
190 CFM class (Air Multiplier 77 gallons/sec circulation)
Coverage area
Coway
1,560 sq ft (2 air changes/hr) / 780 sq ft (4 air changes/hr)
Dyson
500 sq ft room size with 350° oscillation
True 3-Year Cost of Ownership (TCO)
Coway Airmega 400
Dyson Purifier Hot+Cool Formaldehyde HP09
Room Placement & Bedroom Noise Check
Physical clearance required for airflow, wall placement, and bedroom noise levels.
Wall Clearance Required
Requires 12 in perimeter airflow space
Cylindrical base: needs 12 in airflow clearance around unit
Nighttime Sleep Mode Noise
Standard sleep speed
28 dB night mode with dimmed LCD
Unit Footprint & Dimensions
Standard room purifier footprint
Bladeless oval loop (30.0 × 8.1 × 8.1 in; 12.6 lb; heats & cools)
The 90-Day Owner Regret Check
Documented ergonomic quirks, hardware annoyances, and maintenance realities reported by real owners.
Coway: What to watch for
- Maintenance
Requires periodic filter replacements to maintain airflow and odor capture.
Dyson: What to watch for
- Hidden Cost
High replacement filter cost (~$80 each).
Performance
leads 2-0| CADR | 350 CFM (Smoke), 328 CFM (Dust), 400 CFM (Pollen) (wins this row: higher) | 190 CFM class (Air Multiplier 77 gallons/sec circulation) |
|---|---|---|
| Room size | Large living rooms, open floor plans, offices | Medium to large bedrooms, living rooms up to 500 sq ft |
| Coverage area | 1,560 sq ft (2 air changes/hr) / 780 sq ft (4 air changes/hr) (wins this row: higher) | 500 sq ft room size with 350° oscillation |
Filters
2 differences| Filter types | Washable Pre-filter + Max2 Filter (True HEPA + Activated Carbon) | 360° Glass HEPA H13 + Activated Carbon + Cryptomic Formaldehyde filter |
|---|---|---|
| Filter life | 12 months (Max2 filter) / Washable pre-filters | 12 months (HEPA/Carbon) / Permanent Formaldehyde catalyst |
Usability & Smart
leads 1-0| Noise levels | 22 dB (Sleep mode) – 52 dB (Max speed) (wins this row: lower) | 46 dB (Low) – 62 dB (Max) |
|---|---|---|
| Energy consumption | 66 W max power consumption (Energy Star Certified) | 40 W (Purifier mode) / 1,575 W (Heating mode) |
| Smart features | Smart Auto Mode + Eco Mode (no Wi-Fi app) | MyDyson App, voice control via Alexa, Google Assistant, Siri Shortcuts |
| Air quality sensors | Real-time particle sensor with colorful LED ring indicator | Solid-state formaldehyde sensor, PM2.5, PM10, VOC, NO2, Temperature, Humidity |
Design & Ownership
2 differences| Weight | 24.7 lb (11.2 kg) | 12.6 lb (5.7 kg) (wins this row: lower) |
|---|---|---|
| Warranty | 5 years limited motor / 1 year electronic parts (wins this row: higher) | 2 years |
Which one should you buy
Pick this one if
Coway Airmega 400
Dual-suction large room air purifier with Max2 HEPA and activated carbon filtration covering 1,560 sq ft.
- Massive CADR cleans up to 1,560 sq ft twice per hour
- Dual-sided air intake with combined True HEPA and carbon filters
- Smart Eco mode turns off fan when air remains clean for 30 minutes
What you give up
- Cube design has a large floor footprint
- No mobile app connectivity on the non-S model
Pick this one if
Dyson Purifier Hot+Cool Formaldehyde HP09
3-in-1 purifier, ceramic space heater, and cooling fan with solid-state catalytic formaldehyde sensor.
- Combines HEPA H13 purification, fast ceramic heating, and cooling fan in one
- Destroys formaldehyde continuously without filter replacement
- Fully sealed whole-machine HEPA H13 standard prevents bypass
What you give up
- CADR airflow is lower than dedicated box purifiers
- Expensive upfront purchase price
Best for each use
Bedrooms
Tied on bedrooms. Coway Airmega 400 is cheaper.
Big rooms & allergies
For big rooms & allergies, buy the Coway Airmega 400.
Low running cost
Too close to call on low running cost from the spec sheets. Only warranty is rankable here.
Done deciding?
Open the full standalone spec sheet for either device.
Manufacturer pages: Coway Airmega 400 ↗ · Dyson Purifier Hot+Cool Formaldehyde HP09 ↗
Common questions
Which is cheaper, the Coway Airmega 400 or the Dyson Purifier Hot+Cool Formaldehyde HP09?
Coway Airmega 400 costs $250 less at list price.
What is the biggest catch with the Coway Airmega 400 or Dyson Purifier Hot+Cool Formaldehyde HP09?
Coway Airmega 400 has this deal-breaker: no Wi-Fi app. No schedules or remote control from your phone.
Which is better for bedrooms, the Coway Airmega 400 or the Dyson Purifier Hot+Cool Formaldehyde HP09?
Tied on bedrooms. Coway Airmega 400 is cheaper. The 2 rankable bedrooms specs split 1 to 1. Saves $250 at list price.
What cannot be compared from spec sheets?
Of the 11 specs tracked here, 6 are descriptive and cannot be ranked on numbers alone. Spec sheets also cannot measure subjective factors like build quality, real-world performance, or comfort.