Air Purifiers · Head-to-head
Blueair Blue Signature Large (SP4i) vs Coway Airmega Mighty2 AP-1512N
Quietest High-Airflow Pick
Blueair Blue Signature Large (SP4i)
7.8/10
$439.99 at Amazon
Check price at Amazon
The short answer
Coway Airmega Mighty2 AP-1512N comes out ahead overall with 8.0/10 against 7.8/10 for the Blueair Blue Signature Large (SP4i). Blueair Blue Signature Large (SP4i) is stronger on noise at sleep-usable speeds, cleaning performance for bedroom size and sleep-friendly features. Coway Airmega Mighty2 AP-1512N is stronger on indoor-air safety & materials, running cost & ownership and value. At current verified prices, the Coway Airmega Mighty2 AP-1512N costs about $170.00 less.
- Choose the Blueair Blue Signature Large (SP4i) if: Light sleepers with a large primary bedroom who will pay for the most quiet airflow and accept an always-on ionizer.
- Choose the Coway Airmega Mighty2 AP-1512N if: Most people with a 150–400 sq ft bedroom who want the most clean air at a sleep-tolerable noise level, with no ionizer and no need for an app.
Scores by criterion
| Criterion | Blueair Blue Signature Large (SP4i) | Coway Airmega Mighty2 AP-1512N |
|---|---|---|
| Noise at sleep-usable speeds | 9.3HouseFresh: 229 cfm at 40 dB, 34.8 dB in sleep mode. | 8.6HouseFresh: 35.9 dBA in Sleep mode and 151 cfm at 42.6 dBA on speed 2. |
| Cleaning performance for bedroom size | 9.0455 smoke CADR rated; 229 cfm measured at a quiet 40 dB. | 7.5About 151 cfm at quiet speed 2 (99 cfm on speed 1); 260 cfm only at a loud 56.9 dBA. |
| Sleep-friendly features | 8.3Night mode, laser PM2.5 sensor, app. | 7.8Sleep mode and light sensor, but Smart mode forces sleep in the dark, the buttons are unlit and there is no app. |
| Indoor-air safety & materials | 5.0Ionizer cannot be switched off (HouseFresh). | 9.0No ionizer (HouseFresh); combined HEPA and carbon filter. |
| Running cost & ownership | 5.5About $180 a year in filters (HouseFresh). | 7.0$69.99 yearly filter, but HouseFresh rates it the most expensive mid-size unit to own in year one ($415.07). |
| Value | 5.8$439.99 on Amazon. | 7.3$269.99 sold by Amazon; costs more but gives the most quiet airflow without an ionizer. |
Specifications
| Spec | Blueair Blue Signature Large (SP4i) | Coway Airmega Mighty2 AP-1512N |
|---|---|---|
| Exact model / SKU | — | AP-1512N |
| Workflow type | — | Standard Room |
| Lowest-speed noise (manufacturer) | 23 dB | 19 dB |
| Independent PM1 CADR at maximum | — | 237 CFM |
| Top-speed noise (manufacturer) | 55 dB | 50 dB |
| Independent PM1 CADR at low-noise setting | — | 165 CFM |
| Lowest-speed noise (independent measurement) | 34.8 dBA | 35.9 dBA |
| Quiet-test threshold | — | ≤45 dBA |
| CADR (smoke where given, else headline) | 455 cfm | 240 cfm |
| Measured noise range | — | 19–50 decibels |
| Recommended room size (4.8–5 ACH / AHAM) | 705 sq ft | 390 sq ft |
| AHAM-certified smoke CADR | — | 240 CFM |
| Max power draw | — | 56 W |
| Ionization/electronic stage present | — | No |
| Sleep / night mode | Yes | Yes |
| App control | Yes | No |
| Model-specific ozone/technology disclosure | — | CARB classification: Mechanical (G-26-044) |
| Ionizer / electrostatic stage | Ionizer that cannot be disabled (per HouseFresh) | None (removed vs original Mighty, per HouseFresh) |
| Particle-filter construction/certification | — | Washable pre-filter plus Max2 activated-carbon and IEST-certified HEPA filtration |
| Filter type | 7-stage filter incl. pelleted carbon | Washable pre-filter + Max2 combined activated carbon/HEPA |
| Carbon-media format | — | Activated-carbon pellets |
| Main filter life | — | 12 months |
| OEM replacement-filter price | — | 69.99 USD |
| Stated filter interval | — | 12 months |
| Manufacturer direct/list price | — | 269.99 USD |
| Dated US street price | — | 269.99 USD |
| Washable / removable pet pre-filter | — | Yes |
| Activated carbon amount (where disclosed) | — | Not disclosed |
Blueair Blue Signature Large (SP4i)
Pros
- 34.8 dB in sleep mode
- About 229 cfm at 40 dB
- Large coverage
- App control and PM2.5 sensor
- Doubles as a side table
Cons
- Ionizer cannot be turned off
- Premium price
- About $180 a year in filters
- Tabletop surface scratches easily
The quietest high-airflow option for a big room, but only for buyers who accept the always-on ionizer and the cost.
Full Blueair Blue Signature Large (SP4i) review →Coway Airmega Mighty2 AP-1512N
Pros
- Standard-room workflow
- Mechanical-filtration path
- Distinct exact-model corroborating sources
Cons
- Current ownership conditions require publication-time confirmation
- No cross-publisher quietness ranking is made
Recommended for standard-room use based on firsthand HouseFresh evidence and a distinct exact-model WIRED review.
Full Coway Airmega Mighty2 AP-1512N review →Both products are part of our guide The Best Quiet Air Purifiers for Bedrooms of 2026, where you can see every pick, how we score and current prices from each retailer.