Alen BreatheSmart 45i Review: Strong Mid-Size Purifier, Strings Attached
Alen BreatheSmart 45i review: Alen's 245 cfm CADR, five filter options from $69, 1.1 to 50 W, a Forever Guarantee tied to a filter subscription, and no AHAM listing.
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Specs at a glance
- CADR (Alen)
- 245 cfm
- AHAM Verifide listing
- No Alen models in AHAM's directory (checked November 3, 2026)
- Alen coverage
- 800 sq ft every 30 minutes; 1,600 to 1,900 sq ft an hour
- Noise
- About 23 to 50 dBA (Alen)
- Power
- 1.1 to 50 W (Alen support page)
- Filters
- Essential, Advanced, Ultimate and others, $69 to $119 (Alen)
- Ionizer
- Yes; California lists the 45i V2 as an electronic air cleaner
- Warranty
- Forever Guarantee with registration and an active filter subscription (Alen)
The Alen BreatheSmart 45i is a capable purifier for a living room or large bedroom, with one of the best filter menus on the market: you pick a filter for allergies, odors or smoke and swap it in the same body. Alen states a CADR of 245 cfm, about the same as a Winix 5510 or Levoit Vital 200S-P.
Two things hold it back. That CADR is Alen's own figure; no Alen model was in the AHAM Verifide directory when we searched. And Alen's headline "Forever Guarantee" only applies while you register the purifier and keep an active Alen filter subscription. At its price, the certified rivals give you more airflow for the money.
What the 45i is
The 45i is a square tower with a front panel available in several colors and wood finishes. Air enters through the front, passes a pre-filter, a medical-grade HEPA filter and, depending on the filter you choose, a carbon layer, and leaves through the top. A particle sensor drives an auto mode, and a light ring shows air quality. Alen fits an ionizer that you can switch on or off, which is why California's Air Resources Board lists the 45i V2 as an electronic air cleaner (certification G-25-209).
Alen 45i CADR and coverage
Alen's support page lists a CADR of 245 and coverage of about 800 sq ft every 30 minutes or 1,600 sq ft an hour; its collection page gives 950 to 1,900 sq ft. Alen does not say which of AHAM's three CADR figures (smoke, dust or pollen) the 245 refers to, and with no AHAM listing we cannot check it. Treated as a smoke CADR, it gives the following:
| Room | Floor area | Air changes an hour |
|---|---|---|
| Main bedroom, 14 x 18 ft | 252 sq ft | 7.3 |
| Living room, 16 x 20 ft | 320 sq ft | 5.7 |
| Living room, 18 x 21 ft | 378 sq ft | 4.9 |
| Open plan, 20 x 25 ft | 500 sq ft | 3.7 |
So the 45i suits rooms up to about 380 sq ft at the five air changes an hour we recommend for allergies. Alen's 1,600 to 1,900 sq ft figures are one air change an hour. Our sizing calculator runs the numbers for your room.
The filter menu
Alen's strength is choice. The 45i takes several filter types, Essential (particles), Advanced (adds carbon for VOCs and smoke), Ultimate and others aimed at odor or mold, priced from $69 to $119 on Alen's store, with 10% off on subscription. That lets one purifier serve a pet household, a smoker's apartment or a wildfire-prone home without buying a different machine. Amazon sells the 45i bundled with different filters, so check which one is in the box.
The Forever Guarantee, read closely
Alen markets a lifetime warranty. Its terms, as Alen's pages describe them, require that you register the purifier and keep an active filter subscription with Alen. Cancel the subscription and the guarantee lapses. That is a fair trade if you were going to buy Alen filters anyway; it is a reason for caution if you hoped to shop around for filters. Read the current terms on Alen's site before you buy.
Noise and power
Alen gives about 23 to 24 dBA on the lowest speed and 49 to 50 dBA on the highest, and its support page lists 1.1 to 50 W (a product listing gives 1.6 to 64 W). Both are good figures, in line with the efficient Levoit and Blueair models.
Three-year cost
| Item | Essential filter | Premium filter |
|---|---|---|
| Filters, 3 years | $207 | $357 |
| Electricity, 3 years (worst case) | up to $113 | up to $113 |
| Running cost, 3 years | about $320 | about $470 |
Alen 45i vs the alternatives
| Model | Smoke CADR | Room size | Warranty |
|---|---|---|---|
| Alen BreatheSmart 45i | 245 cfm (Alen) | About 380 sq ft at 4.8 ACH (our arithmetic) | Forever, with subscription |
| Winix 5510 | 253 cfm | 392 sq ft | 2 years |
| Levoit Vital 200S-P | 250 cfm | 388 sq ft | 2 years |
| Honeywell HPA300 | 300 cfm | 465 sq ft | 5 years |
| Alen BreatheSmart 75i | 347 cfm (Alen) | About 540 sq ft (our arithmetic) | Forever, with subscription |
Who should buy the Alen BreatheSmart 45i
- Buy it if you want one purifier you can tune with the right filter for allergies, odors or smoke, and you are happy to buy filters from Alen.
- Buy it if looks matter; the wood and color panels suit a living room.
- Skip it if you want a certified CADR; the Winix 5510 and Levoit Vital 200S-P are AHAM listed at similar airflow for less.
- Skip it if you want no ionizer in the house, or switch the ionizer off and keep it off.
- Bigger room? See the Alen 75i review.
Frequently asked questions
What is the CADR of the Alen 45i?
Alen lists a CADR of 245 cfm. No Alen model was in AHAM's Verifide directory when we searched on November 3, 2026, so the figure is Alen's own.
What size room does the Alen BreatheSmart 45i cover?
Alen says about 800 sq ft every 30 minutes, or 1,600 to 1,900 sq ft an hour. At the five air changes an hour recommended for allergies, 245 cfm suits a room of about 380 sq ft with 8 ft ceilings.
What is Alen's Forever Guarantee?
A lifetime warranty that, as Alen describes it, requires product registration and an active Alen filter subscription. If the subscription lapses, so does the guarantee; check the current terms on Alen's site.
Does the Alen 45i have an ionizer?
Yes, and it can be switched off. California lists the 45i V2 as an electronic air cleaner, meaning it was tested against the 0.050 ppm ozone emission limit.
How much are Alen 45i filters?
Alen lists its 45i filters from $69 to $119 depending on type, with 10% off on subscription.
Is the Alen 45i quiet?
Alen gives about 23 to 24 dBA on the lowest speed and 49 to 50 dBA on the highest, which is quiet at the low end.
Sources
- BreatheSmart 45i - Alen air purifier, Alen
- Alen BreatheSmart 45i HEPA Air Purifier, Alen
- Alen Air Purifier Comparison, Alen
- AHAM Verifide Directory: Certified Room Air Cleaners, Association of Home Appliance Manufacturers
- List of CARB-Certified Air Cleaning Devices, California Air Resources Board
Related guides
Alen BreatheSmart 75i Review: Big-Room Purifier, Big-Room Price
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