1Rank 01 of 10 · Air Purifiers
Bosch Air 4000
The only purifier in this ranking with a documented Stiftung Warentest result: test winner in 3/2024 with 2.3 (gut) and, according to Bosch, still on top in 5/2026. A plain 300 m³/h machine without an app, sold for under €200.
8.4BPR score
- €198Price
- 300 m³/h — published by Bosch; not independently certified on the product pageParticle CADR in m³/h, as published by the manufacturer
- 1 of 10in Air Purifiers
- 8.4BPR score 0–10
Review
What this product is
Written after the analysis, from the same sources the score is built on: the manufacturer's documentation, available studies and verified owner feedback.
The Air 4000 suits buyers who want a purifier for a bedroom or a medium living room and would rather rely on a consumer-test result than on a spec sheet. Bosch publishes a CADR of 300 m³/h and a room size of 62.5 m²; that room figure assumes only two air changes per hour. At five changes per hour the same machine covers about 25 m², which is the honest size to plan with.
The filter is a single 3-in-1 cartridge with pre-filter, activated carbon and a layer Bosch calls HEPA 13. Noise is given as 25 dB(A) in sleep mode and 49 dB(A) as the upper figure; power draw is 2 to 26 W according to the otto.de listing. Stiftung Warentest named it test winner in issue 3/2024 with 2.3 (gut) and singled out the lowest power consumption in the field; Bosch reports that it kept that position in 5/2026. Austria's Konsument rated it gut (64 %), first of six, in 4/2024. We saw these grades via Bosch and testberichte.de, not in the paywalled reports.
What is missing: the product page states neither a filter replacement interval nor a filter price, there is no app on this version, and no CADR for a used filter.
Technical data
Specification
Figures from the manufacturer's documentation, verified against available outside sources. Values we could not confirm are marked as declared.
- Particle CADR
- 300 m³/h
- Room size claimed
- 62.5 m²
- Room size at 5 air changes/h (2.4 m ceiling)
- about 25 m² (our calculation)
- Filter
- 3-in-1: pre-filter, activated carbon, HEPA 13 layer
- Noise
- 25 dB(A) sleep mode; 49 dB(A) maximum figure
- Power
- 2–26 W (otto.de listing)
- Weight
- 4 kg
- Dimensions
- 500 × 291 mm (H × W)
- Modes
- automatic, sleep, timer, child lock
- Air-quality display
- LED colour ring
- Filter interval
- not published on the product page
- Stiftung Warentest
- 2.3 (gut), test winner 3/2024 and 5/2026 (per Bosch)
Component scores
Where the score
comes from.
Four components, equal weight, each on a 0–10 scale and each resting on a named source. The overall score is their mean — the full procedure is in the methodology.
What we liked
- Stiftung Warentest test winner 3/2024 with 2.3 (gut), confirmed in 5/2026 according to Bosch
- Konsument 4/2024: gut (64 %), first of six
- Low draw of 2–26 W and 25 dB(A) in sleep mode
- Filter layer stated as HEPA 13, not just 'HEPA'
- 4.7 stars from 720 Amazon.de ratings (via testberichte.de); €197.55 at otto.de
Worth knowing
- 62.5 m² claim assumes two air changes per hour; about 25 m² at five
- Filter interval and filter price not stated on the product page
- No app or remote control on this version
- Test grades seen second-hand only; the reports are behind a paywall
Comparison
How it compares
within the category
All values come from the same analysis and are comparable only within the category Air Purifiers.
| Product | Score | Particle CADR in m³/h, as published by the manufacturer | Price |
|---|---|---|---|
| Air 4000This product · top score | 8.4 | 300 m³/h — published by Bosch; not independently certified on the product page | €198 |
| Core 400SRunner-up | 7.8 | 400 m³/h — published by Levoit; no certification mark on the EU page | €220 |
| Category average10 products analysed | 7.4 | — | — |
FAQ
Frequently asked questions
Is the Bosch Air 4000 really enough for 62.5 m²?
Only if two air changes per hour are enough for you. 300 m³/h divided by 62.5 m² and a 2.4 m ceiling gives exactly 2.0 changes per hour. For allergy or smoke use, plan with about 25 m².
What exactly did Stiftung Warentest award?
According to Bosch and testberichte.de, the Air 4000 was test winner in issue 3/2024 with 2.3 (gut) and 'Umwelttipp' for the lowest power consumption, and it remained the best-rated available model in 5/2026. We could not read the paywalled report itself.
From the same ranking
Other products in Air Purifiers.
The same protocol, the same key parameter, the same set of sources.
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No. 027.8/ 10
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The highest published CADR in the ranking, 520 m³/h for €249, in a 6.2 kg tower with ECARF…
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Blue Pure 511i Max
A 1.9 kg bedroom purifier that draws 17 W and still publishes about 260 m³/h for smoke…