Quick Answer
If you are choosing between the Coway Airmega 100 and Coway Airmega 150 for a small flat, the Airmega 150 is the better choice for the main living room, especially if you have pets, visible dust, or allergies. The Airmega 100 still makes sense for a small bedroom, nursery, office, or a second purifier where price and footprint matter more than coverage.
The short version: use the Airmega 150 where people and pets spend the most time, and only choose the Airmega 100 for smaller closed rooms. In a compact apartment, two smaller purifiers can work better than one large machine, but the individual room size still matters.
Why Room Size Matters More Than Flat Size
Air purifiers clean the room they are sitting in. They do not reliably pull dusty air from a bedroom, hallway, and living room through one doorway unless airflow is unusually open. That is why a 530 square foot flat usually needs one purifier in the living room and another in the bedroom if both spaces matter.
The useful sizing number is CADR, or Clean Air Delivery Rate. AHAM's simple rule is that the smoke CADR should be at least two-thirds of the room's floor area for normal 8 foot ceilings. For wildfire smoke, stronger sizing is better, but for everyday dust, pollen, and pet dander, that two-thirds rule is a solid baseline.
Coway Airmega 100: Best For Small Closed Rooms
The Coway Airmega 100 is Coway's compact cylindrical purifier. Coway lists it at $129.99 in the U.S. and describes it as a small-space model with 360-degree intake, a three-stage filter system, and particle capture down to 0.01 microns based on filter media claims.
Independent test listings commonly put the Airmega 100 around 109 CFM CADR. That is enough for a bedroom around 150 to 170 square feet if you are comfortable running it at higher fan speeds when needed. It is a reasonable pick for a small bedroom, spare room, or office where the door is often closed.
Where the Airmega 100 starts to feel limited is a main living area with pets. Dog hair, tracked-in dust, sofa fabric, rugs, and open doorways all add load. A smaller purifier can still help, but it may need to run louder and longer to keep up.
Coway Airmega 150: Better For The Main Room
The Coway Airmega 150 costs more, with Coway's U.S. page listing it at $189.99. The higher price buys a stronger bedroom/living-space purifier with a pre-filter, deodorization filter, HEPA filter, filter indicators, auto speed control, and an air quality light that can be turned off.
Coway says the Airmega 150 can maintain pure air in spaces up to 214 square feet. Spec sheets and retailer listings commonly show CADR figures around 138 for smoke, 161 for dust, and 219 for pollen. For a living room around 170 square feet, that gives the Airmega 150 more breathing room than the Airmega 100, especially for dust and pet dander.
It is not overkill for a small flat. Oversizing slightly is useful because you can often run the purifier on a lower, quieter setting while still moving a meaningful amount of air. That matters more in living rooms and bedrooms where high fan noise gets annoying.
Which Setup Should You Buy?
For a small flat with a living room around 16 square meters and a similar-size bedroom, the most sensible setup is usually one Airmega 150 in the living room and one Airmega 100 or 150 in the bedroom. Choose the second Airmega 150 if allergies, pet dander, pollen, or dust are serious. Choose the Airmega 100 if the bedroom is the cleaner room and budget is tight.
The two-pack Airmega 100 bundle is tempting, but it is best when both rooms are modest, closed-off, and you are not expecting strong pet-hair performance in the main room. If the living room is where a dog spends most of the day, start with the larger unit there.
What About Pet Hair And Dust?
An air purifier catches airborne particles; it does not replace vacuuming or brushing pets. For pet hair, the washable pre-filter is important because it catches larger fluff before it reaches the HEPA filter. Clean the pre-filter regularly, and keep the purifier off the floor if the intake design allows enough clearance and stable placement.
For dust, expect reduction, not magic. Heavy dust settles onto floors and shelves before a purifier can catch it. The purifier helps most with fine suspended dust, pollen, dander, and particles kicked up by movement. Running it continuously on a quiet setting usually works better than blasting it for an hour after the room already feels dusty.
Bottom Line
Buy the Coway Airmega 150 for the living room in a small flat, especially if you have a dog, dust, or allergy concerns. Use the Airmega 100 as the budget-friendly bedroom or office option. If you can afford two Airmega 150 units, that is the cleaner and quieter long-term setup for two regularly used rooms.