Comparison · 03 contenders · air purifier
Three air purifiers sized for a bedroom
Three purifiers compared on stated coverage, filter cost per year and published noise figures — plus why those noise numbers are not comparable.
Quang Sang1 min
The pick
Q40
The Wren Q40 wins on the figure that keeps costing money: replacement filters are the cheapest here per year, by enough to pay back its higher purchase price inside two years. It is the largest of the three and its stated coverage is more than a bedroom needs, which is the trade.
- Price
- $249as of Jan 14, 2026
- Score
- 8.6/ 10
- Best for
- Lowest running cost
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Scoreboard
Spec matrix
3 contenders · 7 rows
| Spec | Q40 | Mini | Tower |
|---|---|---|---|
| PriceSpec | $249 | $149 | $199 |
| Stated coverageSpec | 40 m² | 20 m² | 32 m² |
| Filter cost per yearSpec | $45 | $90 | $68 |
| Stated noise, lowSpec | 24 dB | 27 dB | 29 dB |
| Stated noise, highSpec | 52 dB | 55 dB | 58 dB |
| FootprintSpec | 34 × 34 cm | 24 × 24 cm | 26 × 26 cm |
| WarrantySpec | 3 years | 2 years | 2 years |
Spec — manufacturer-published. Hands-on — observed here, not measured. Highlighted cells lead their row.
Contender breakdown
Wren Q40
The pick · Best for — Lowest running cost
8.6
Strengths
- Cheapest filters per year by a wide margin
- Lowest stated noise on its quiet setting
- Filter change is tool-free
Trade-offs
- Largest footprint of the three
- Highest purchase price
$249Example Store →
Solace Mini
Best for — Small rooms and small budgets
8.0
Strengths
- Cheapest to buy
- Smallest footprint here
Trade-offs
- Most expensive filters per year
- Stated coverage is marginal for a large bedroom
$149
Harlow Tower
Best for — Tall rooms
7.5
Strengths
- Tallest outlet, moves air further
- Mid-priced filters
Trade-offs
- Loudest stated figure at full speed
- Filter change needs a screwdriver
$199
The purchase price of an air purifier is the smaller half of what it costs. The filter schedule is the other half, it repeats every year, and it is published by all three makers — which makes it the most comparable row in the table.
Why the noise column is a trap
All three publish decibel figures. None publish the same test. One states its figure at one metre, one at “typical listening distance”, and one does not say. They are in the matrix because omitting a published figure is its own kind of distortion, but no cell in that column is marked as a winner, because there is no honest basis to pick one.
Sizing, briefly
Stated coverage assumes a ceiling height and an air-change rate that each maker picks. Treating it as a rough sort rather than a specification is the safe reading: the Wren is comfortably oversized for a bedroom, the Harlow is about right, and the Solace is at its limit.
What this comparison does not cover
Particulate performance of any kind. Measuring that needs equipment this site does not own, so no claim about it appears anywhere in this article.
Questions
Are the noise figures comparable?
No, and they are in the table anyway because they are what the makers publish. Each states noise at a distance and on a setting it chooses, and none of the three publish the same test conditions. Read the column as three separate claims, not one ranking.
Does higher stated coverage help in a smaller room?
It means the unit reaches the same result on a lower, quieter setting — which in a bedroom is the whole point. It does not mean the air gets cleaner than clean.
How was filter cost per year worked out?
From each maker's own replacement schedule and its own list price for the filter. It assumes you follow the schedule and buy at list, which is the pessimistic case.