Home & KitchenDecision tool

Which air purifier should you buy? Answer 4 questions

For a bedroom or home office up to about 220 square feet, the answer is almost always the Levoit Core 300S. These four questions check whether your room needs more output, like the Coway Mighty or the Blueair 211i Max, or whether the budget Core 300 will do.

Decision tool

Question 1 of 4

How big is the room?

Count only the room where the purifier will sit.

The questions

1. How big is the room? · Count only the room where the purifier will sit.
Bedroom or office up to 220 sq ftLiving room, 220 to 400 sq ftOpen plan over 400 sq ftNot sure
2. What's the main reason?
Pollen and allergiesPet hair and danderSmoke and cooking smellsDust and city air
3. Will it run while you sleep?
Yes, in the bedroomNo, daytime in the living areaDoesn't matter
4. What's your top budget? · Market price ranges, not Amazon prices.
As little as possibleMid-rangeI can spend more for a big roomPrice isn't the point

What we recommend, profile by profile

How big is the room?

Bedroom or office up to 220 sq ft
ideal Levoit Core 300S: Sized for bedrooms up to 219 square feet, with a laser sensor that runs auto mode and a genuinely quiet sleep setting.; Xiaomi Smart Air Purifier 4 Compact: Costs less and performs well at quiet speeds.; Levoit Core 300: The Core 300S filter and body at a budget price, with simple touch controls and no app.
acceptable Coway Airmega AP-1512HH Mighty
Living room, 220 to 400 sq ft
ideal Xiaomi Smart Air Purifier 4 Pro: Double the output for large rooms.; Coway Airmega AP-1512HH Mighty: Roughly twice the Levoit's output, rated for 361 square feet, with auto and eco modes.
acceptable Levoit Core 300S, Blueair Blue Pure 211i Max
Open plan over 400 sq ft
ideal Xiaomi Smart Air Purifier 4 Pro: Double the output for large rooms.; Blueair Blue Pure 211i Max: The highest output here, rated for 674 square feet, with PM1, PM2.5 and PM10 sensors and a Wi-Fi app.
acceptable Coway Airmega AP-1512HH Mighty
Not sure
ideal Coway Airmega AP-1512HH Mighty: Roughly twice the Levoit's output, rated for 361 square feet, with auto and eco modes.
acceptable Levoit Core 300S, Xiaomi Smart Air Purifier 4 Compact, Xiaomi Smart Air Purifier 4 Pro, Levoit Core 300, Blueair Blue Pure 211i Max

What's the main reason?

Pollen and allergies
ideal Levoit Core 300S: Sized for bedrooms up to 219 square feet, with a laser sensor that runs auto mode and a genuinely quiet sleep setting.; Xiaomi Smart Air Purifier 4 Pro: Double the output for large rooms.; Coway Airmega AP-1512HH Mighty: Roughly twice the Levoit's output, rated for 361 square feet, with auto and eco modes.; Blueair Blue Pure 211i Max: The highest output here, rated for 674 square feet, with PM1, PM2.5 and PM10 sensors and a Wi-Fi app.
acceptable Xiaomi Smart Air Purifier 4 Compact, Levoit Core 300
Pet hair and dander
ideal Xiaomi Smart Air Purifier 4 Pro: Double the output for large rooms.; Coway Airmega AP-1512HH Mighty: Roughly twice the Levoit's output, rated for 361 square feet, with auto and eco modes.; Blueair Blue Pure 211i Max: The highest output here, rated for 674 square feet, with PM1, PM2.5 and PM10 sensors and a Wi-Fi app.
acceptable Levoit Core 300S, Xiaomi Smart Air Purifier 4 Compact, Levoit Core 300
Smoke and cooking smells
ideal Xiaomi Smart Air Purifier 4 Pro: Double the output for large rooms.; Blueair Blue Pure 211i Max: The highest output here, rated for 674 square feet, with PM1, PM2.5 and PM10 sensors and a Wi-Fi app.
acceptable Coway Airmega AP-1512HH Mighty
Dust and city air
ideal Xiaomi Smart Air Purifier 4 Compact: Costs less and performs well at quiet speeds.; Levoit Core 300: The Core 300S filter and body at a budget price, with simple touch controls and no app.
acceptable Levoit Core 300S, Xiaomi Smart Air Purifier 4 Pro, Coway Airmega AP-1512HH Mighty, Blueair Blue Pure 211i Max

Will it run while you sleep?

Yes, in the bedroom
ideal Levoit Core 300S: Sized for bedrooms up to 219 square feet, with a laser sensor that runs auto mode and a genuinely quiet sleep setting.; Xiaomi Smart Air Purifier 4 Compact: Costs less and performs well at quiet speeds.; Levoit Core 300: The Core 300S filter and body at a budget price, with simple touch controls and no app.
acceptable Blueair Blue Pure 211i Max
No, daytime in the living area
ideal Xiaomi Smart Air Purifier 4 Pro: Double the output for large rooms.; Coway Airmega AP-1512HH Mighty: Roughly twice the Levoit's output, rated for 361 square feet, with auto and eco modes.; Blueair Blue Pure 211i Max: The highest output here, rated for 674 square feet, with PM1, PM2.5 and PM10 sensors and a Wi-Fi app.
acceptable Levoit Core 300S, Xiaomi Smart Air Purifier 4 Compact
Doesn't matter
ideal Levoit Core 300S: Sized for bedrooms up to 219 square feet, with a laser sensor that runs auto mode and a genuinely quiet sleep setting.
acceptable Xiaomi Smart Air Purifier 4 Compact, Xiaomi Smart Air Purifier 4 Pro, Levoit Core 300, Coway Airmega AP-1512HH Mighty, Blueair Blue Pure 211i Max

Products considered

Product	Best for	Why for you	The catch	Price band
Levoit Core 300S Coverage: Up to 219 sq ft (4.8 ACH) · Filter: Pre-filter, HEPA-type, activated carbon · Functions: Laser PM2.5 sensor, auto, sleep, timer See on Amazon → · Read the full guide	For bedrooms and home offices	Sized for bedrooms up to 219 square feet, with a laser sensor that runs auto mode and a genuinely quiet sleep setting.	Thin carbon layer: strong smoke and cooking smells overwhelm it.	Budget pick
Xiaomi Smart Air Purifier 4 Compact Coverage: 230 m³/h CADR · 170–290 sq ft · Filter: Pre-filter, HEPA, activated carbon · Functions: Laser particle sensor, auto, sleep Search on →	–	Costs less and performs well at quiet speeds.	Manual speeds live in the app.	–
Xiaomi Smart Air Purifier 4 Pro Coverage: 500 m³/h CADR · 375–650 sq ft · Filter: Pre-filter, HEPA, activated carbon · Functions: PM2.5 and PM10 sensors, OLED display, auto, sleep Search on →	–	Double the output for large rooms.	Tall and heavy.	–
Levoit Core 300 Coverage: Up to 219 sq ft (4.8 ACH) · Filter: Pre-filter, HEPA-type, activated carbon · Functions: 3 speeds, sleep, timer (no sensor) See on Amazon → · Read the full guide	For a nursery on a budget	The Core 300S filter and body at a budget price, with simple touch controls and no app.	No air quality sensor, so no auto mode.	Budget pick
Coway Airmega AP-1512HH Mighty Coverage: 361 sq ft (4.8 ACH) · CADR 233 smoke · Filter: Pre-filter, carbon, True HEPA, optional ionizer · Functions: Air quality sensor, auto, eco, timer See on Amazon → · Read the full guide	For living rooms	Roughly twice the Levoit's output, rated for 361 square feet, with auto and eco modes.	No app, loud on high, and the optional ionizer should stay off.	Mid-range
Blueair Blue Pure 211i Max Coverage: 674 sq ft (4.8 ACH) · CADR 435 smoke · Filter: Washable pre-filter, HEPASilent particle and carbon filter · Functions: PM1/PM2.5/PM10 sensors, auto, night See on Amazon → · Read the full guide	For open-plan spaces	The highest output here, rated for 674 square feet, with PM1, PM2.5 and PM10 sensors and a Wi-Fi app.	Bulky, with filters in the high price bracket.	Premium

Manufacturer-stated data checked against official spec sheets; prices as market ranges. Analysis based on specifications and verified reviews, not on hands-on testing.

How we chose the questions

The tool matches your answers against the spec sheets of the purifiers in our guide. Room size carries the most weight because it decides how much CADR you need: under the AHAM standard a purifier should swap the room's air about five times an hour, and an undersized one sits on max, loud and ineffective. The reason you're buying comes next. Every True HEPA filter in our picks handles pollen and pet dander, while smoke and cooking odors call for more activated carbon, which you get in the larger models. The third question is about sleep: we favor models with a quiet sleep mode and lights you can switch off, and we mark down machines too big or too loud to sit next to a bed. Budget is a hard filter based on typical market price ranges, not today's Amazon price, so anything above your limit drops out. Ties go to the order in the guide. Amazon links are affiliate links, but the commission never changes the result.

How the score works

Each answer gives 2 points to the product that is ideal for that profile, 1 to an acceptable one and 0 to one that does not cover it. Budget is eliminatory: anything above it is out. Ties go to the guide's order. Amazon links are affiliate links, but the result does not depend on the commission.

Frequently asked questions

Does the tool account for sales?

No. It uses typical market price ranges, so the advice still holds after a sale ends.

Can I move one purifier between rooms?

Yes, if it's light like the Levoit Core 300S or Core 300. Size it for the larger of the two rooms.

Why does room size matter so much?

Because an undersized purifier can't swap the air often enough, even on max.

This tool comes from the guide: Best air purifier for your room: which one to buy for allergies. Updated 26 October 2026.

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