Alen BreatheSmart 75i Review
The most expensive machine we cover, read against the register rather than the brochure. We do not test units; here is what the premium actually buys.
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The premium here buys documentation and filter choice, not airflow. 370 certified smoke CADR across 574 certified square feet is good but not category-leading; the 12-15 month filter life, the four filter compositions and the switchable ionizer with a published ozone figure are things almost nothing else offers. It measures 1 ppb rather than zero.
The disclosure first: we have not tested this unit. We own no air purifiers and run no laboratory. What follows is the ENERGY STAR record plus what Alen publishes, each labeled — our method, including where it runs out.
The certified record
| Specification | Figure | Source |
|---|---|---|
| Smoke CADR | 370 CFM | ENERGY STAR |
| Dust CADR | 351 CFM | ENERGY STAR |
| Pollen CADR | 431 CFM | ENERGY STAR |
| PM2.5 CADR | 360 CFM | ENERGY STAR |
| Certified room size | 574 sq ft | ENERGY STAR, at 4.8 ACH |
| Two-thirds-rule room | 555 sq ft | Our arithmetic on the CADR |
| Annual energy use | 304 kWh | ENERGY STAR |
| Electricity per year | $56 | Our arithmetic at a named rate |
| Air per watt | 6.9 CFM/W | ENERGY STAR |
| Measured ozone | 1 ppb | ENERGY STAR |
| Filter classification | HEPA-Type | ENERGY STAR |
| Power draw | 1.36 to 55 W across five speeds | Alen |
| Noise | 25-51 dBA | Alen |
| Filter life | 12-15 months (Pure), 7-10 months (Fresh, Odor) | Alen |
| Filter price | $99 (Pure), $139 (Odor) | Alen |
| Ionizer | Included, documented as switchable | Alen |
| Size and weight | 27 in tall, 18.5 in wide, 11.5 in deep, 27 lb | Alen |
Electricity costs on this page use 18.34¢ per kWh, the U.S. average residential price for June 2026 from the U.S. Energy Information Administration, Electric Power Monthly, Table 5.3. Your rate is on your bill and is probably not this one; multiply the kWh figure by your own rate and you have your number.
The filter economics, which are the point
Almost every machine on this site hides half its running cost, because manufacturers publish a filter price or an interval but rarely both. Alen publishes both, for every filter it sells. That makes the 75i one of only two machines we cover whose annual cost of ownership can be computed rather than guessed.
| Filter | Published life | Price | Filters per year | Annual cost |
|---|---|---|---|---|
| Pure (standard) | 12-15 months | $99 | 0.9 | $88 + $56 power |
| Odor (carbon) | 7-10 months | $139 | 1.4 | $196 + $56 power |
Two things follow. The carbon option roughly doubles the filter bill, so buy it only if odor is genuinely the problem. And a 12-15 month standard interval is the longest documented life on this site — worth real money against machines whose interval nobody publishes at all.
The ionizer, and why we credit Alen for it
The 75i includes an ionizer. That would normally be a mark against a machine on this site. Alen does two things almost nobody else does: it documents the stage as switchable, and it publishes the ozone figure in both states — “0 PPM when disengaged, less than 0.001 PPM with ionizer engaged”.
ENERGY STAR independently measures 1 ppb, which is consistent with a machine tested with the stage on. Compare that with the Blueair Max range, where the two registers disagree about whether an ion generator exists at all and no manufacturer statement resolves it. An ion stage you can turn off, with a published number attached, is a different proposition from one you cannot — how we weigh ionizers, ozone and the marketing around both.
Where the premium does not buy anything
Airflow per dollar. 370 certified CFM is beaten by the Blueair 211i Max at 435 and matched closely by the LEVOIT Core 600S at 391, both for a fraction of the price. If certified air is what you are buying, this is not the efficient way to buy it.
Efficiency. 6.9 CFM per watt is respectable and well behind the 9.0 the Blueair posts. At $56 a year in electricity it is mid-table on running cost before filters.
The filter classification. The register records HEPA-Type, not HEPA, despite “medical-grade” language in the marketing. The Honeywells at a quarter of the price are recorded HEPA — what the two classifications mean.
The coverage claim. 2,800 square feet every hour is nearly five times the 574 the register certifies, because it is computed at one air change an hour. Alen prints the honest figure in its specifications, but the headline is the one buyers read.
Who should buy it
Buy it if you want the longest documented filter interval available, you want to choose a carbon-heavy or allergen-focused filter rather than accept one cartridge, and you value an ionizer you can switch off over a machine that never had one.
Buy something else if you are buying certified airflow: the Core 600S covers 606 square feet with a measured zero for far less, and the Coway Airmega 450 covers 687 with the same zero.
The guarantee, and the subscription attached to it
Alen markets a “Forever Guarantee”, and its own product page conditions it on product registration and an active air filter subscription. That is worth reading twice before it factors into a purchase decision: a lifetime warranty that lapses if you stop buying filters on schedule is a different product from a lifetime warranty.
It is not necessarily a bad deal. On a machine whose filters Alen prices at $99 to $139 and dates at 7 to 15 months, a subscription mostly formalizes a purchase you were going to make anyway, and the filter economics on this page assume you make it. But it belongs in the price comparison, because the cheaper machines on this site carry no such condition — and neither do they carry the guarantee.
Quick picks
The 75i against the two machines that deliver comparable air for less money.
| # | Product | Best for | Certified CADR | Price |
|---|---|---|---|---|
| 1 |  The unit reviewed Alen BreatheSmart 75i 370 certified CFM, a 12-15 month filter, and an ionizer you can switch off. | Very large rooms, long filter intervals | 370CFM smoke ENERGY STAR verified | |
| 2 |  Similar air, measured zero, less money LEVOIT Core 600S 391 certified CFM across 606 sq ft with 0.00 ppb and no ion stage. | Large open-plan rooms | 391CFM smoke ENERGY STAR verified | |
| 3 |  More certified room, same zero Coway Airmega 450 443 certified CFM across 687 sq ft, vacuumable pre-filter. | Open-plan floors up to about 665 sq ft | 443CFM smoke ENERGY STAR verified |
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The alternatives worth weighing
LEVOIT Core 600S
LEVOIT · model Core 600S (LAP-C601S-WUS)
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391 certified smoke CADR is real large-room capability, and it is honest about needing 387 kWh a year to deliver it — the highest electricity bill of any LEVOIT we cover.
391 smoke / 398 dust / 436 pollen CFM · 394 PM2.5
- Certified room size
- 606 sq ft
- Advertised coverage
- 2,909 sq ft at 1 air change per hour
- Energy / year
- 387 kWh
- Electricity / year
- $71
- Air per watt
- 6 CFM/W
- Power draw
- 49 W
- Noise
- 26-55 dB
- Measured ozone
- 0 ppb
- Filter class
- HEPA-Type
- AHAM rule, 550 sq ft
- Clears it (367 needed)
No ionizer — filtration only
ENERGY STAR classifies this unit 'Fan and Filter', 0.00 ppb measured ozone.
391 certified smoke CADR across 606 certified square feet with 0.00 ppb measured and no ion stage at all, now listed in both registers, with a published dB range and a published filter price. The full record on it.
The honest con: $71 a year is more electricity than the Alen, LEVOIT publishes no filter interval so the annual filter cost cannot be computed, and there is no washable pre-filter documented.
Coway Airmega 450
Coway · model Airmega 450 (AP-2524B)
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687 certified square feet with zero measured ozone and a vacuumable pre-filter. The step between the Airmega 400 and the ProX, and the cheapest certified way past 600 square feet.
443 smoke / 445 dust / 450 pollen CFM · 444 PM2.5
- Certified room size
- 687 sq ft
- Advertised coverage
- 3,285 sq ft in 60 minutes
- Energy / year
- 389 kWh
- Electricity / year
- $71
- Air per watt
- 6.7 CFM/W
- Power draw
- 72 W
- Noise
- 23.6-57.7 dB(A)
- Measured ozone
- 0 ppb
- Filter class
- HEPA-Type
- AHAM rule, 650 sq ft
- Clears it (434 needed)
No ionizer — filtration only
ENERGY STAR classifies this unit 'Fan and Filter' and measures 0.00 ppb ozone. Coway's specification lists no ionizing stage.
443 certified smoke CADR across 687 certified square feet — more air and more room than the Alen — with 0.00 ppb measured, no ion stage, a vacuumable pre-filter and a choice of three filter sets. Our full review.
The honest con: its published noise range tops out at 57.7 dB(A), the loudest we print, and Coway publishes no replacement filter price for it — so unlike the Alen, its annual cost cannot be computed.
Common questions
Is the Alen BreatheSmart 75i worth the money?
How long do Alen 75i filters last, and what do they cost?
Does the Alen 75i produce ozone?
What room size is the BreatheSmart 75i for?
Sources
- ENERGY STAR certified room air cleaners database
- AHAM — air filtration standards and the two-thirds rule
- Alen BreatheSmart 75i specification
- EPA — Guide to Air Cleaners in the Home
Figures were read on the dates shown against each source. If one has changed, or if we have got something wrong, tell us and we will correct the page.
Read next
- AllergiesThe Best Air Purifiers for SmokeRanked on certified smoke CADR — the standard's own primary particle — with an honest account of what filtration leaves behind.
- AllergiesThe Best Air Purifiers for AllergiesThe flagship roundup: certified CADR, measured ozone, computed running cost, and the coverage claims checked against the registers.
- CADR & costWhat air purifier filters actually costFilter interval and price arithmetic, with the assumptions stated and the gaps admitted.