Coway Airmega 250S vs Levoit Core 400S-P: Bedroom or Living Room?

For a bedroom, buy the Levoit Core 400S-P: it moves about 47% more air than the Coway Airmega 250S while staying under 45 dBA, weighs roughly half as much and usually costs less up front. The Coway makes more sense in a living room where the purifier has to stand flat against a wall and cooking smells are the main nuisance. At typical street prices, their three-year bills land within a dollar of each other.

The short answer

Choose the Core 400S-P if the purifier will run while you sleep or work, it can stand out from the wall where its all-round intake can breathe, you want four fan speeds with smaller jumps between them, or you like having pet, toxin and smoke versions of the filter to choose from.

Choose the Airmega 250S if it has to fit a shallow spot behind a sofa or beside a TV stand, smells bother you more than dust, you value a 3-year motor warranty over Levoit's 2 years, and you can find it near $270 instead of $449.

On paper	Coway Airmega 250S	Levoit Core 400S-P
Smoke / dust / pollen CADR	249 / 261 / 230 CFM	231 / 240 / 259 CFM (AHAM Verifide)
Room size at 4.8 air changes/hr	~386 sq ft	~358 sq ft
Airflow under 45 dBA (HouseFresh)	~91 CFM on speed 1	~134 CFM (original Core 400S)
Rated noise	22 to 54 dB	22 to 52 dB
Rated maximum power	64 W	38 W
Shape and size	Flat panel: 18.5 in wide, 8.3 in deep, 19.7 in tall	Round tower, 10.8 x 10.8 x 20.5 in
Weight	20.5 lb	11 lb (Levoit manual)
Fan settings	Sleep plus 3 speeds	Sleep plus 4 speeds
Sensors	Particle plus gas	Laser PM2.5
App	Coway IoCare+	Levoit VeSync
Filter	Max2: $89, 6 to 12 months	Core 400S-RF: $49.99, 6 to 8 months
Price	$449 list; about $271 at Target (Sept 2026)	$219.99 list; $189.99 common
Warranty	Motor and electronics 3 years; rest 1 year	2 years limited

Quiet airflow is what decides a bedroom

Rated CADR only describes top speed, and nobody sleeps next to top speed. HouseFresh estimated how much each delivers while staying under 45 dBA: about 91 CFM for the 250S and about 134 CFM for the Core 400S. That second figure comes from the original Core 400S, which shares the -P's body, fan and filter; No hardware change between the two has been documented by Levoit.

Converted to room size at 4.8 air changes an hour, that is roughly 141 sq ft of quiet coverage for the Coway against 208 sq ft for the Levoit. In practice:

• 12 x 15 bedroom (180 sq ft): about 3.8 quiet air changes an hour from the 250S and 5.6 from the Core 400S-P. Only the Levoit meets the target without getting loud.
• 14 x 16 primary bedroom (224 sq ft): 3.0 against 4.5. Neither quite gets there quietly, but the Levoit comes much closer.

The reason shows up in HouseFresh's step-by-step readings at 3 ft:

Setting	Airmega 250S	Core 400S
Sleep	35.7 dBA	35.5 dBA
Speed 1	36.5 dBA	38.3 dBA
Speed 2	50.2 dBA	43.2 dBA
Speed 3	59.3 dBA	51.2 dBA
Speed 4	n/a	60.3 dBA

Between numbered speeds the Levoit climbs 5 to 9 dB at a time; the Coway leaps almost 14 dB from speed 1 to speed 2. When auto mode kicks up at 2 a.m., the Levoit's next step is far easier to sleep through. The air changes calculator shows what your own room gets at any CFM.

Living rooms and where each one stands

At full power the gap reverses slightly. A 15 x 23 living room (345 sq ft) gets about 5.4 air changes an hour from the 250S and 5.0 from the Core 400S-P, so both qualify. An 18 x 22 room (396 sq ft) is past both: 4.7 and 4.4.

Placement is the bigger difference. Air enters the Core 400S-P from every side of its 10.8 in base, so it works in the middle of a room or beside a sofa arm, but loses some of that advantage tucked into a corner. The 250S is a flat panel only 8.3 in deep, shaped to stand against a wall like a side table, which suits a narrow hallway or the gap between a couch and the wall. The placement guide covers distance from walls and vents.

Three-year cost: a near tie at street prices

Assumptions: street prices ($271 for the Coway at Target, $189.99 for the Levoit); each unit's bundled filter counts as the first one; Coway's Max2 lasts 12 months (two replacements) and Levoit's filter 7 months, the middle of its 6 to 8 month guidance (five replacements); each runs nonstop on its loudest setting under 45 dBA in HouseFresh's testing, speed 1 on the 250S (6.52 W) and speed 2 on the Levoit (8.51 W); $0.17/kWh.

Three years	Airmega 250S	Core 400S-P
Purchase	$271	$189.99
Filters	2 x $89 = $178	5 x $49.99 = $249.95
Electricity	~$29	~$38
Total	~$478	~$478

The Coway's cheaper running costs on paper are only real if its filter lasts a full year. If its indicator asks for a new Max2 every six months, five cartridges ($445) push it to about $745. Stretch the Levoit filter to eight months and you buy four instead of five, for about $428.

At list prices ($449 against $219.99), the Coway costs about $148 more over three years, which removes the tie. Swap in Levoit's $64.99 Smoke Remover filter and the Levoit total rises by about $75. Test other intervals with the filter cost calculator.

Sensors, odors and the two apps

The 250S's gas sensor lets auto mode respond to cooking and solvent smells, not just particles. HouseFresh also notes pelleted carbon in its Max2 filter. The Levoit reads PM2.5 with a laser sensor and nothing else, so a strong smell with little smoke may not register. Some owners say the reading sits at its cleanest level even during cooking; a sensor clean, not a new purifier, is the usual cure.

Levoit's answer on odors is filter choice: the standard Core 400S-RF includes activated carbon, and Toxin Absorber ($59.99) and Smoke Remover ($64.99) versions exist for tougher jobs. Coway sells one Max2 filter for the 250S.

Neither app is flawless. A recurring VeSync complaint is a dropped connection that needs re-pairing; the recurring IoCare+ complaint, which HouseFresh ran into, is being logged out. Both offer schedules, remote control and voice assistants once they behave.

Names and parts that cause mistakes

• PlasmaPro 400S. A model called PlasmaPro 400S, or PlasmaPro 400S-P, turns up at Best Buy and Home Depot: it is this body with an ionizer added. The Core 400S-P and the 250S have none. Background on why that matters is in the ionizer and ozone safety guide.
• One Levoit filter fits four models. The Levoit Core 400S Replacement Filter goes into either Core 400S version and either PlasmaPro.
• Pre-filters differ. The Coway's slides out and can be washed. Levoit's is bonded to the filter cylinder, so vacuuming is the only option.
• Coway serial codes. Coway support ties the Max2 to serial numbers showing 02F9S or 02F9R after the opening three digits; a unit with any other code needs a different filter.
• Carrying weight. At 20.5 lb, the 250S is nearly twice the Levoit's 11 lb, which matters if it moves between rooms.

Which one to buy

For a bedroom, nursery or home office, the Core 400S-P: more clean air at whisper levels, a gentler noise curve, and a lower price at list or on sale. Buy the 250S for a living room where a flat profile matters and smells are the problem, but only near its street price; at $449 the numbers stop working.

If neither fits, two other machines cover the same room size. The Levoit Vital 200S-P rates 250 CFM, roughly 388 sq ft, and its pre-filter rinses clean, which suits pet owners. The Winix 5530 (253 CFM, about 392 sq ft) matches the 250S's 8.3 in depth for wall placement, though its PlasmaWave ionizer should be switched off if you want purely mechanical filtration. For rooms past 400 sq ft, move up to the Levoit Core 600S.