Alen 45i Air Purifier: CADR, Noise, Coverage & Specs
Last verified: Aug 23, 2026
Aug 2026
Quick verdict
The Alen 45i is best suited to medium rooms where high airflow, quiet minimum operation, and app control are priorities. Its 255 CFM smoke CADR supports about 395 sq ft at approximately 4.8 air changes per hour. Buyers should separately evaluate filter cost and maximum-speed noise before deciding.
Best for
- Living rooms and medium bedrooms
- Low-noise minimum settings
- App or Wi-Fi control
Consider alternatives if
- You need a verified maximum-speed noise figure
- Filter replacement interval or cost is a deciding factor
- You are planning around the manufacturer coverage claim rather than CADR-based room size
Verified strengths
- 255 CFM smoke CADR (~395 sq ft at ~4.8 ACH)
- 23 dB published minimum noise
- HEPA filtration (as published)
- Wi-Fi or app control
Verified limitations or missing information
- Maximum-speed noise is not in our sources
- Filter replacement interval is not verified
Alen 45i overview
The Alen 45i is a medium-room air purifier with a smoke CADR of 255 CFM. Based on our CADR-based room-size method, it is suitable for approximately 395 sq ft. It includes HEPA filtration, 23 dB minimum noise, and Wi-Fi or app support.
- Smoke CADR
- 255 CFM
- Recommended room size
- 395 sq ft
- Claimed coverage
- 1900 sq ft
- Minimum noise
- 23 dB
- Filter type
- HEPA
- Wi-Fi / app
- Yes
- Weight
- 14 lb
- Last verified
- Aug 23, 2026
Alen 45i CADR and room size
Recommended room size is about 395 sq ft (CADR × 1.55). That is approximately 4.8 air changes per hour in a room with an eight-foot ceiling. The manufacturer figure of 1900 sq ft corresponds to about 1.0 air change per hour at the same ceiling height and is shown separately. Our recommended room size uses approximately 4.8 air changes per hour with an eight-foot ceiling. Manufacturer coverage figures may use a lower air-change rate and are shown separately.
The manufacturer coverage claim is higher than 3× CADR, so it is not used for ranking.
Alen 45i noise level
Published minimum noise is 23 dB.
Maximum-speed noise is not in our sources.
Alen 45i filtration
Published filter type: HEPA.
Filter replacement interval is not verified in our sources.
Alen 45i smart features
True HEPA filtration, Whisper-quiet operation, Smart Sensor, Auto Mode
Alen 45i specifications
- CADR (smoke)
- 255 CFM
- Recommended room size
- 395 sq ft
- Manufacturer claimed coverage
- 1900 sq ft
- Minimum noise
- 23 dB
- Filter type
- HEPA
- Weight
- 14 lb
- Wi-Fi / app
- Yes
About Alen air purifiers
Alen models in this catalog are compared by CADR, recommended room size, noise, and filter type.
Alen 45i comparisons
What is the CADR of the Alen 45i?
Smoke CADR is 255 CFM.
What room size is the Alen 45i suitable for?
About 395 sq ft at approximately 4.8 air changes per hour with an eight-foot ceiling.
How loud is the Alen 45i?
Minimum reported noise: 23 dB.
Does the Alen 45i have Wi-Fi?
Yes — app or Wi-Fi features are listed.
What filter does the Alen 45i use?
HEPA.
Methodology
Specifications are compiled from manufacturer documentation, product listings and other cited sources.
How we calculate recommended room size.
Sources
All air purifiers · Best air purifiers for allergies · Methodology