Alen BreatheSmart 45i Review — Now Replaced by the BreatheSmart 25i

The Alen BreatheSmart 45i has been discontinued. Its successor, the Alen BreatheSmart 25i, takes a different approach: smaller coverage, lower price, and significantly quieter operation. At $184, the 25i costs nearly half what the 45i did — and it adds app-connected smart sensors that the 45i never had. Here is our full assessment of what has changed and whether the 25i is worth buying.

What Changed: 45i vs 25i

The BreatheSmart 25i is not a direct upgrade — it is a repositioning. Here is how the two models compare:

The 25i trades raw airflow and large-room coverage for a much lower price, quieter operation, and modern smart connectivity. If you previously considered the 45i for large rooms, the 25i is better suited to bedrooms, offices, and mid-size living spaces up to 400 sq. ft.

Design & Smart Features

The BreatheSmart 25i retains Alen's signature customizable front panels — 14 color and material options let you match the purifier to your decor. The overall footprint is more compact than the 45i, making it easier to tuck beside furniture or place in a corner.

The biggest upgrade over the 45i is app-connected smart sensors. The 25i connects to the Alen app via Wi-Fi, providing real-time air quality readings, filter life tracking, and remote control. This was the 45i's most frequently cited weakness, and the 25i addresses it directly. You can now schedule operation, monitor air quality trends, and receive filter replacement reminders from your phone.

Air Cleaning Performance

With a CADR of 107, the BreatheSmart 25i is designed for rooms up to 400 square feet — bedrooms, home offices, and smaller living areas. This is a significant step down from the 45i's 245 CADR and 800 sq. ft. rating. If you need large-room coverage, the Coway Airmega 400 or Blueair Blue Pure 211+ are better choices.

Within its rated coverage, the 25i performs well. The True H13 HEPA filter captures 99.97% of particles at 0.3 microns, and the activated carbon layer handles odors and light VOCs. The smart sensors detect air quality changes and adjust fan speed automatically — a genuine improvement over the 45i's basic color-ring indicator.

Noise Levels

This is where the 25i genuinely excels. At 20 dB on its lowest setting, it is one of the quietest air purifiers we have encountered — quieter than the 45i's already-impressive 25 dB low. Even at maximum speed, the 25i tops out at 40 dB, which is quieter than the 45i's speed 3 setting.

For bedroom use, the 25i is exceptional. The 20 dB low setting is effectively inaudible from across a room, making it ideal for light sleepers.

Filter Options & Replacement Costs

Alen continues to offer customizable filter options for the 25i, each designed for different air quality concerns. Annual filter costs remain competitive, and the 12-month filter lifespan means minimal maintenance.

Energy consumption is modest, and the smart app tracks filter life so you never have to guess when a replacement is due.

Who Should Buy This

The Alen BreatheSmart 25i is ideal for:

• Budget-conscious buyers — At $184, it undercuts the Coway Mighty ($230) and Levoit Core 400S ($220)
• Bedroom users — 20 dB is among the quietest in any price range
• Smart home users — App-connected sensors address the 45i's biggest weakness
• Mid-size rooms — 400 sq. ft. covers most bedrooms, offices, and apartments
• Design-conscious buyers — 14 customizable panel options

It is NOT ideal for:

• Large room owners — 400 sq. ft. and 107 CADR are insufficient for spaces over 400 sq. ft.
• Heavy smoke or VOC concerns — The lower CADR limits its effectiveness for heavy-duty air cleaning
• Anyone needing maximum airflow — The Levoit Core 400S or Blueair Blue Pure 211+ move more air

Pros and Cons

How It Compares

The BreatheSmart 25i fills a different niche than the 45i did. It is now the most affordable option in this comparison, and the quietest. The Coway and Winix offer more airflow and larger coverage. The Levoit Core 400S matches the 25i on smart features while delivering higher CADR. The 25i's advantage is its combination of low price, ultra-quiet operation, and app connectivity — a balance no single competitor matches.

The Verdict

After extensive research and analysis, here is the AirQualityNest editorial team's verdict.

The BreatheSmart 25i is a smart pivot from Alen. By dropping the price to $184 and adding app connectivity, they have created a compelling option for buyers who prioritize quiet operation and smart features over raw airflow. It will not clean a 800 sq. ft. living room the way the 45i could, but for bedrooms, home offices, and apartments up to 400 sq. ft., it delivers effective HEPA filtration at a price that is hard to argue with.

The Forever Guarantee with filter subscription provides long-term peace of mind — Alen will replace the unit if it fails while you maintain an active filter subscription. Combined with the low purchase price, the 25i offers strong long-term value.