Match CADR to room size first — an undersized purifier on its highest setting still won't out-clean an oversized one on low.
An air purifier's real-world performance comes down to two numbers most buyers skip: CADR (Clean Air Delivery Rate, how much filtered air it actually moves per hour) matched against the room's actual size, and the ongoing filter replacement cost over the unit's lifetime, which for a cheap purifier can exceed the purchase price within a couple of years.
The category splits broadly into HEPA-filter models (the standard for genuine particulate removal, including allergens, dust and smoke) and models that add activated carbon (for odours and some VOCs) or, on a few higher-end units, additional sensors for automatic speed adjustment based on measured air quality rather than a fixed schedule.
Manufacturers state a recommended room size for each model, usually alongside the raw CADR figure. Buying for the room it will actually sit in, not the biggest room in the house on the assumption it'll get moved around, gives a far more accurate expectation of real performance.
True HEPA filtration
A genuine HEPA filter (removing at least 99.95% of particles down to 0.3 microns under the European EN 1822 standard, or a broadly equivalent claim) is the baseline worth checking for explicitly; some budget units use a lesser "HEPA-type" or "HEPA-like" filter that doesn't meet the actual standard.
Filter replacement cost and interval
Add up the manufacturer's recommended filter replacement interval and current replacement filter price over two to three years of ownership; this ongoing cost varies enormously between brands and can flip which model is actually cheaper overall.
Activated carbon for odours and VOCs
A separate or combined activated carbon layer targets odours and some volatile organic compounds that a HEPA filter alone, which is a purely particulate filter, doesn't address. Worth prioritising for cooking odours, pet smells, or a home near a busy road with traffic fumes.
Automatic mode with a real air quality sensor
The most useful automation adjusts fan speed based on an actual onboard particulate sensor's reading, ramping up when air quality drops and idling quietly the rest of the time. A cosmetic colour-changing light ring that isn't tied to a real sensor reading is a lesser feature, worth distinguishing from genuine auto mode.
Noise at the setting you'll actually use
Check decibel ratings at the speed setting realistic for continuous use (often the lowest one or two settings), not just the headline maximum-speed figure, particularly for bedroom placement.
The shortlist compared
Brand
Model
Filtration
Room size
Auto mode sensor
Indicative price
IKEA
STARKVIND
True HEPA + activated carbon
up to ~32 m²
No (basic 3-speed)
€100–170
Philips
Series 3000i / 2000i
True HEPA + activated carbon
up to ~49–79 m²
Yes, real-time PM sensor
€250–400
Xiaomi/Smartmi
Air Purifier 4 series
True HEPA
up to ~48 m²
Yes, real-time PM sensor
€150–250
Levoit
Core series
True HEPA + activated carbon
up to ~50–65 m²
Yes on higher tiers
€120–250
Blueair
Blue series
HEPASilent (proprietary)
up to ~50–80 m²
Yes, real-time PM sensor
€250–450
Prices move constantly and vary by country, so we give an indicative band
rather than a figure that would be stale within a month. Check the brand's own store for the
current price.
The picks in detail
IKEA STARKVIND
Zigbee (Matter via IKEA hub)
IKEA's purifier is the accessible entry point with genuine true-HEPA filtration and, unusually for the price tier, a version that doubles as a side table, at a price well below the premium brands.
It lacks a real-time particulate sensor for genuine auto mode, running on a basic 3-speed setting instead, and Zigbee integration via IKEA's DIRIGERA hub is a nice touch for existing IKEA smart home users specifically.
Cheapest genuine true-HEPA purifier in this comparison
Zigbee/Matter integration via IKEA's hub
Table variant doubles as furniture
No real-time particulate sensor for genuine auto mode
Smaller recommended room size than the premium alternatives
Philips Series 3000i / 2000i
Wi-Fi
Philips' purifiers pair genuine true-HEPA and activated carbon filtration with a real-time particulate sensor driving a genuinely responsive auto mode, and the app clearly displays current measured air quality rather than a vague indicator light.
It's priced at a premium over IKEA and Xiaomi for a comparable room-size rating, reflecting the more capable sensor and generally more polished build.
Real-time particulate sensor with clearly displayed readings
True HEPA plus activated carbon as standard
Scales to larger rooms at the higher-tier models
Priced above IKEA/Xiaomi for a comparable room size
Filter replacement cost is on the higher side
Xiaomi/Smartmi Air Purifier 4 series
Wi-Fi
Xiaomi's range undercuts Philips and Blueair on price while still including a genuine real-time particulate sensor and true-HEPA filtration, making it a strong value pick for a mid-sized room.
App and account setup goes through Xiaomi's ecosystem, which some buyers find less polished or trust-inspiring than Philips' or Blueair's, and third-party smart-home integration varies by exact model and region.
Genuine real-time particulate sensor at a lower price than Philips/Blueair
True HEPA filtration as standard
Good value for a mid-sized room
App/account ecosystem less polished, and regional feature availability can vary
Filter genuineness/counterfeit concerns exist for third-party replacement filters, buy from official channels
Levoit Core series
Wi-Fi
Levoit has built a strong reputation for straightforward, reliable purifiers at a competitive price, with true-HEPA and activated carbon filtration standard across the range and a real-time sensor on the higher tiers specifically.
The entry-level Core models in the range skip the real-time sensor, so check the exact model tier rather than assuming the whole Core range includes it.
Competitive pricing across a wide range of room sizes
Real-time sensor available on higher-tier models
Widely available replacement filters
Entry-level tier lacks the real-time sensor, check the specific model
Build quality solid but not distinctive
Blueair Blue series
Wi-Fi
Blueair's proprietary HEPASilent filtration combines mechanical and electrostatic filtering to achieve strong particulate removal at a lower noise level than many pure-mechanical HEPA competitors at a comparable CADR, which matters for continuous bedroom or office use.
It's priced at the premium end of this comparison, and Blueair's washable pre-filter is a nice ongoing-cost saver, though the main HEPASilent filter itself still needs periodic replacement.
Genuinely quieter operation at a comparable CADR to HEPA-only competitors
Washable pre-filter reduces some ongoing filter cost
Real-time particulate sensor with clear app display
Priced at the premium end of this comparison
Proprietary filter design ties you to Blueair's own replacement filters
Check the manufacturer's stated recommended room size for the specific model, which is usually based on achieving a reasonable number of air changes per hour at that room's volume, and buy for the room it will actually live in rather than the largest room in the house.
Is a real HEPA filter necessary?
For genuine particulate removal (allergens, fine dust, smoke), yes — look specifically for a stated "true HEPA" or EN 1822 compliance claim rather than a vaguer "HEPA-type" or "HEPA-like" description, which doesn't guarantee the same filtration standard.
How much do replacement filters cost over time?
It varies enormously by brand and model, and is worth calculating over two to three years of ownership rather than judging on purchase price alone — a cheaper purifier with frequent, expensive filter replacements can end up costing more overall than a pricier model with a longer filter life.
Should I run it constantly or only when needed?
Running a correctly sized purifier continuously on a lower, quieter setting generally achieves better average air quality than running an undersized one occasionally on its highest, loudest setting. Continuous low-level operation is usually the more effective and more livable approach.
Does an air purifier help with odours as well as particles?
A HEPA filter alone targets particulates, not gases or odours. A separate or combined activated carbon layer is what actually addresses cooking smells, pet odours and some volatile organic compounds, so check for it explicitly if odour control specifically is a priority.
Terms explained
CADR (Clean Air Delivery Rate)
A measure of how much filtered air a purifier delivers per hour, used to match a unit's real-world capability to a specific room size.
True HEPA
A filter meeting a defined standard (commonly 99.95% or better removal of particles down to 0.3 microns under EN 1822 in Europe) as opposed to an unregulated "HEPA-type" claim that doesn't guarantee the same performance.
Activated carbon
A filter material with a porous structure that adsorbs odours, gases and some volatile organic compounds, complementing a HEPA filter's particulate-only filtration.
Air changes per hour (ACH)
How many times a purifier can theoretically filter the full volume of air in a given room within one hour, a useful way to compare sizing beyond the raw CADR figure alone.
