The short answer
- About $1,331 to own over five years: $799 to buy, $136 in electricity, $396 in filters. The most expensive here.
- The Forever Guarantee is conditional. It requires product registration and an active filter subscription.
- CADR 375 is the highest of the six, and Alen is the only one here that publishes power across every speed.
Who this is for
The 75i is for a large open room, up to roughly 590 square feet at a genuine 4.8 air changes an hour, where you want the fastest cleaning in this group and you were always going to buy filters on schedule. On those terms it is a good machine and the guarantee is worth something.
On any other terms, read the guarantee before the specifications. Alen’s Forever Guarantee is stated on the product page as applying with product registration and active air filter subscription. A lifetime warranty that lapses when you stop buying consumables is a different product from a lifetime warranty.
What the specifications actually say
CADR is published as 375, the highest figure in this set. Alen does not say which particle type it refers to, which matters: smoke is the hardest of the three and the number most worth quoting. We report it as published rather than assuming it is the smoke figure.
Alen does one thing here that nobody else does. It publishes the full power range, 1.36 W at the bottom to 55 W at the top, instead of a single maximum. Our model uses the 55 W ceiling, so the electricity line below is an upper bound rather than a typical figure.
| Specification | Value | Source |
|---|---|---|
| CADR | 375 | Alen product page, retrieved 31 Aug 2026; particle type not stated |
| Coverage claim | 1,400 sq ft every 30 minutes | Alen product page |
| Coverage at 4.8 ACH | 586 sq ft | Calculated from CADR 375 at an 8 ft ceiling |
| Power draw | 1.36 W to 55 W across speeds | Alen product page |
| Filter life (Essential) | 12-15 months at 24/7 use | Alen product page |
| Filter life (Advanced, Ultimate) | 7-10 months at 24/7 use | Alen product page |
| Replacement filter (Essential) | $99.00 | Alen product page, retrieved 31 Aug 2026 |
| Warranty | Forever Guarantee, with registration and active filter subscription | Alen product page |
| Certifications | Energy Star Most Efficient 2025, Quiet Mark, asthma and allergy friendly | Alen product page |
| Price | $799 | Merchant listing at publication |
The cost nobody quotes
Five years, at the US average of $0.17 per kWh, running eight hours a day, on the Essential filter at a twelve-month interval.
What it really costs over 5 years
Total$1,331
| Cost | Amount | How we got it |
|---|---|---|
| Purchase price | $799 | Street price at publication |
| Electricity | $136 | 160 kWh/yr at $0.17 per kWh |
| Filters & consumables | $396 | $79 per year |
| Total | $1,331 | $266 per year · $0.09 per session |
Running costs are 40% of the 5-year total. The sticker price is not the decision.
Electricity priced at $0.17 per kWh, the US residential average. Change the rate in the settings to match your utility. Consumable costs come from the manufacturer's published replacement schedule.
Sixty per cent of this total is the machine itself, which is unusual in this category and is the one genuinely good thing about its cost structure: you are not being fed a cheap box and an expensive habit. But $1,331 is still the highest five-year figure of the six, and $282 more than the Austin Air, which costs more to buy.
Choose the Advanced or Ultimate filters instead of the Essential and the interval falls to seven to ten months, which pushes the consumables line up by roughly half again. The cheapest filter is the one Alen quotes.
Certifications, and what they cover
Frequently asked questions
Is the Alen Forever Guarantee really a lifetime warranty?
It is stated on Alen’s product page as applying with product registration and an active air filter subscription. If you stop the subscription, the condition is no longer met.
What does the BreatheSmart 75i cost to run per year?
About $27 in electricity at $0.17 per kWh, running eight hours a day, using the published 55 W maximum (55 W x 56 h/week x 52 = 160 kWh). Real use will be lower.
What room size does it really cover?
About 586 square feet at 4.8 air changes an hour, calculated from the published CADR of 375.
Why do you not test these yourself?
We are a research publication, not a lab. We verify third-party test data, publish the source next to every number, and calculate the costs manufacturers leave out.
