Most air purifiers ask you to choose between performance and something you actually want in your living room. The Blue Signature™ range was built to remove that compromise. It pairs Blueair's HEPASilent™ filtration with a Scandinavian design that earns its place in the room, and it now comes in three sizes so you can match the machine to the space rather than the other way round.

This guide looks at the Blue Signature Small, Medium and Large to help you work out which model is best suited for your home.

What is the Blue Signature range?

Blue Signature is Blueair's premium design-led purifier range. Three sizes cover everything from a box bedroom to an open-plan ground floor:

• Blue Signature™ Small for rooms up to 23 m²
• Blue Signature™ Medium for rooms up to 46 m²
• Blue Signature™ Large for rooms up to 65 m²

All three share the same seven-stage filtration, the same OdorFence™ odour removal technology, the same app and the same Nordic Fog and Midnight finishes. What changes as you go up the range is airflow, the size of the machine and how large a room a single unit can handle. The quality of filtration quality does not change with size, the Small is not a watered-down purifier, it uses the same technology, it just processes less air.

The benefits of the Blue Signature air purifier range

Whichever size you choose, you get the same core technology. This is where the range earns its price.

• Seven stages of filtration: HEPASilent™ technology captures at least 99.97% of airborne particles down to 0.1 microns, including dust, pollen, pet dander, smoke, bacteria and mould allergens.¹ ⁴
• OdorFence™ Technology: adds an extra, patent-pending filter layer that breaks odour gases down at a molecular level rather than simply trapping them, for advanced odour removal.²
• Smart VOC sensing: the purifier continuously detects airborne gases and chemical pollutants in real time, picking up the pollution you cannot see or smell as well as the pollution you can.
• Particle sensing on every model: integrated sensors read fine particulate in real time so Auto mode responds to what is actually in your air rather than a fixed schedule.
• Accurate filter life tracking: filter life is calculated from fan speed, running time and real pollution levels, so you replace the filter when it is genuinely spent and not a day sooner.
• A filter that lasts up to a year: the patent-pending design doubles filter lifetime, with a recommended change every nine to twelve months and a tool-free swap when the time comes.⁶
• Motion-activated display: the touchscreen wakes as you approach, shows your air quality at a glance and dims automatically at night so it never lights up the bedroom.
• Quieter than a whisper on low: 23 dB at the lowest setting rising to 55 dB on boost, with a dedicated Night mode on every model.
• Genuinely low running costs: the Small draws a maximum of 20 W and the Medium and Large run between 3.5 W and 42 W, so on the settings you will be using the majority of the time, they cost less than a light bulb.
• Full smart control: Wi-Fi connectivity, four fan speeds plus Auto and Night, custom schedules, display lock and filter alerts through the Blueair app.
• Customisable design: two colourways plus swappable fabric pre-filters in six shades, so the purifier suits your room instead of fighting it.
• Certified B Corp: Blueair meets independently verified standards for social and environmental performance, and every unit ships with a 30-day home trial.

Independent reviewers have picked up on the design in particular. Yanko Design gave the range its Editor's Choice award, noting that it finally gives design-conscious homeowners a purifier they will not want to hide. In Blueair's own consumer testing, 95% of users felt it contributed to a healthier living environment and 89% preferred it to any other air purifier they had used.⁵

Blue Signature™ Small

The entry point to the range, and the one that makes putting a proper purifier in every bedroom realistic. At 34.8 cm tall and a roughly 24 cm diameter footprint, it sits comfortably on a bedside table, a desk or a shelf, and at 2.6 kg you can move it one-handed.

It clears 23 m² in 12.5 minutes at the AHAM-recommended 4.8 air changes per hour, and up to 110 m² in an hour in a more open space. Clean air delivery rate is 304 m³/h for pollen, 283 m³/h for dust and 271 m³/h for smoke.

The Small also gets one thing the bigger models do not: an Eco mode alongside the usual four speeds plus Auto and Night, which reduces consumption further when air quality is already good.

Key specifications

• Dimensions: 34.8 cm high x 23.9 cm wide x 23.9 cm deep
• Weight: 2.6 kg
• Recommended room size: 23 m² at 4.8 ACH
• Cleans up to: 110 m² in one hour
• CADR: 304 m³/h pollen, 283 m³/h dust, 271 m³/h smoke
• Noise: 23 to 55 dB
• Energy: 20 W maximum
• Speeds: 1, 2, 3, 4, Auto, Night, Eco

Best for: bedrooms, nurseries, box rooms, home offices, studies and student rooms. It is also the model to buy in multiples. Several customers report starting with one unit and ending up with a Small in each bedroom and a Large in the main living space, which is a more effective approach than relying on a single big purifier to serve a whole floor.

Worth knowing: the top surface is small, so treat the Small as a bedside or desk unit rather than a side table. If you want the furniture-style tabletop, look at the Medium or Large.

Blue Signature™ Medium

The middle of the range and a versatile option at 30 cm diameter and 49 cm tall it takes up roughly the footprint of a large plant pot, so it fits a corner or an alcove where a wider purifier would be awkward.

It clears 46 m² in 12.5 minutes and up to 209 m² in an hour, with clean air delivery of 561 m³/h for pollen, 545 m³/h for smoke and 525 m³/h for dust. That is roughly 85% more clean air per hour than the Small.

Key specifications

• Dimensions: 49 cm high x 30 cm wide x 30 cm deep
• Weight: 4.3 kg
• Recommended room size: 46 m² at 4.8 ACH
• Cleans up to: 209 m² in one hour
• CADR: 561 m³/h pollen, 525 m³/h dust, 545 m³/h smoke
• Noise: 23 to 55 dB
• Energy: 3.5 to 42 W
• Speeds: 1, 2, 3, 4, Auto, Night

Best for: main bedrooms, medium to large living rooms, larger home offices and open-plan kitchens in flats. If you are buying one purifier for the room you spend most of your waking hours in, this is usually the right answer.

Blue Signature™ Large

The flagship. It is shorter and wider than the Medium at 44 cm tall on a 40 cm diameter base. This gives it a functionally usable top surface, usable as a side table and the noticeably more powerful fan behind the same filtration system clears a much larger space.

It clears 65 m² in 12.5 minutes and up to 314 m² in an hour, with CADR climbing to 773 m³/h for pollen, 765 m³/h for smoke and 741 m³/h for dust. Recommended room sizes from 67 m² up to 161 m² depending on how many air changes per hour you want.

Key specifications

• Dimensions: 44 cm high x 40 cm wide x 40 cm deep
• Weight: 6 kg
• Recommended room size: 67 to 161 m² (4.8 to 2 ACH)
• Cleans up to: 314 m² in one hour
• CADR: 773 m³/h pollen, 741 m³/h dust, 765 m³/h smoke
• Noise: 23 to 55 dB
• Energy: 3.5 to 42 W
• Speeds: 1, 2, 3, 4, Auto, Night

Best for: open-plan kitchen-diners, large living rooms, converted lofts and knock-through spaces. It is also the model to choose if odours are your main concern, because cooking smells, wood smoke and pet odour all clear faster with more air moving through the OdorFence™ filter. One customer reported kitchen odours dropping to almost nothing within about twenty minutes of switching it on.

The Large features optional bases, so if you want the purifier lifted off the floor on wooden legs or a chrome ring, that is the model to buy.

Blue Signature Small vs Medium vs Large

Which size should you choose?

Measure the room first. Work out the floor area in square metres, then pick the model whose recommended room size meets or exceeds it. A purifier sized for the room spends most of its life on a low, quiet fan speed rather than labouring on boost, which means less noise and lower running costs.

Choose the Small if the room is under about 23 m², it needs to sit on a surface rather than the floor, or you are buying more than one unit to cover several bedrooms.

Choose the Medium if the room is between roughly 23 m² and 46 m², or floor space is tight and you would rather go tall than wide.

Choose the Large if you have an open-plan space, a knock-through, high ceilings or a room over roughly 50 m². Also choose it if odour control is the reason you are buying, or if you want the tabletop and base accessories.

Consider ceiling height. All room-size ratings assume a standard ceiling. If you have a Victorian room with high ceilings or a vaulted loft, size up, because you have more air volume to move than the floor area suggests.

Think about doors. Room-size ratings assume a reasonably enclosed space. If your living room opens onto a hallway and a kitchen with no doors between them, treat the whole area as one room and size accordingly.

One big unit or several small ones?

Air purifiers only clean the air in the room they occupy, so two Smalls in two bedrooms will do more for your household than one Large parked in the hall. The usual pattern is a Large or Medium in the main living space plus a Small in each bedroom.

Colours, pre-filters and accessories

All three purifiers come in Nordic Fog and Midnight. The fabric pre-filter is the part you can swap for a different look, available in Nordic Fog, Warm Grey Dune, Archipelago Taupe, Midnight, Night Waves and Aurora Green.

For the Large, two optional bases lift the unit off the floor and change its character completely:

• Leg Base in Wood: warm timber legs that make the purifier read as a Scandinavian side table rather than an appliance.
• Ring Base in Chrome: a polished metal ring that suits more contemporary and industrial interiors.

Replacement filters last nine to twelve months, so budget for approximately one filter per unit per year as your only ongoing cost.

Getting the best from your Blue Signature

Leave room around it. The 360-degree intake needs roughly 10 cm of clearance on all sides to work properly, so avoid pushing the unit flush against a wall or wedging it between furniture.

Run it on Auto. The sensors handle fan speed far better than guesswork, and Auto keeps energy use and noise down when the air is already clean.

Use Night mode in bedrooms. It caps the fan speed and dims the display so the unit stays at the quiet end of its range while you sleep.

Boost before, not after. If you are cooking, decorating or grooming a pet, switch to a higher speed before you start rather than waiting for the sensor to catch up.

Maintain the pre-filter. The fabric outer layer catches hair and larger dust, which extends the life of the main filter. It vacuums clean in seconds or can be washed on a gentle setting with a mild detergent.

Close the door. A purifier works on the air in its own room. Shutting the bedroom door an hour before bed gives the unit a defined volume to clean rather than an endless supply of hallway air.

Every Blue Signature model ships free next day on orders over £50 and comes with a 30-day home trial, so you can run one in your own space before committing. Shop the Blue Signature™ range

Footnotes

¹ Tested on PM2.5 up to 90 minutes.

² Tested on acetaldehyde gas vs similar leading competitor filter.

³ Based on high-speed CADR by volume vs similar competitive models.

⁴ Tested on bacteria (S. aureus, K. pneumoniae, P.aeruginosa), virus (MS2) and mould allergen (A. niger) with a minimum reduction rate of 99.9% in 60 minutes. Blueair does not claim to prevent transmission of airborne illnesses. Not tested on SARS-CoV-2.

⁵ Based on consumer testing of 38 users over the course of four weeks.

⁶ Compared to Blue Pure 211+.