The Cheapest Air Purifier Is the Worst Value: We Did the CADR-Per-Dollar Math

Air purifiers are sold on sticker price and big coverage claims, but the only number that tells you how much clean air you're actually buying is CADR — Clean Air Delivery Rate, the cubic feet per minute of filtered air a unit moves. So we did the obvious thing no spec sheet does: we divided CADR by price across eight purifiers we track, to see what a unit of clean air actually costs. The result is counterintuitive. The cheapest machine on the list is the single worst value, and "going bigger" costs you nothing per dollar.

Clean air per dollar, ranked

We used each unit's smoke (fine-particle) CADR — the hardest particles to clear, and the most conservative figure — against its current price. Higher CADR-per-dollar means more clean air for your money.

Purifier	Smoke CADR (CFM)	Price	CADR per $	$ per CFM	Coverage
Winix 5510	248	~$180	1.38	$0.73	~372 sq ft
Levoit Core 600S	410	~$300	1.37	$0.73	~635 sq ft
Blueair 211i Max	410	~$300	1.37	$0.73	~635 sq ft
Coway Airmega AP-1512HH	233	~$173	1.34	$0.74	~361 sq ft
Blueair 211+ Auto	350	~$300	1.17	$0.86	~540 sq ft
Blueair 311 Auto	250	~$229	1.09	$0.92	~388 sq ft
Levoit Core 300S	141	~$130	1.08	$0.92	~219 sq ft
Levoit Core Mini	45	~$50	0.90	$1.11	~60–80 sq ft

Four things the math shows

1. The $50 purifier is the most expensive clean air on the list. The Levoit Core Mini delivers 0.90 CADR per dollar — 53% less than the Winix 5510's 1.38. Put another way, a unit of clean air from the Mini costs $1.11; from the Winix it's $0.73. The low sticker hides the worst rate in the category, because a tiny fan moves very little air no matter how little it costs. The Mini is a fine personal device for the air right in front of you; it is not a cheap way to clean a room.

2. Going bigger doesn't cost you a value premium. This is the surprise. The ~$300 large units — the Levoit Core 600S and Blueair 211i Max — deliver the exact same 1.37 CADR per dollar as the small ~$173 Coway. You're buying more coverage essentially at cost, not paying a markup for size. If your room is big, the right-sized unit isn't the "expensive" choice on a per-clean-air basis — it's the same deal in a bigger box.

3. "Smart" is roughly free. The Blueair 211i Max packs Wi-Fi, an app, and PM1/2.5/10 sensing, and still lands at the same 1.37 CADR per dollar as the no-frills Levoit 600S. Whatever you make of app control, you're not sacrificing clean-air value to get it at this tier.

4. The value sweet spot is the $170–300 room unit. Everything from the Coway up through the big Blueair clusters tightly at 1.34–1.38 CADR per dollar. Below that line — the $130 Core 300S, the $229 311 Auto, the $50 Mini — the rate falls, because you're paying for small size, whisper-quiet operation, or a low sticker rather than throughput. The Winix 5510 just edges the top of the pack: ~370 sq ft of coverage and a washable pet-hair pre-filter for about $180.

How we did this

CADR is the AHAM-verified, apples-to-apples measure of how much filtered air a purifier delivers. We used the smoke CADR — the figure for the smallest, hardest-to-capture particles — for every unit that publishes one; the Winix and the Mini use independent lab estimates, noted in the table. We then divided by current price. This is deliberately a value lens, not a fit recommendation: a higher rate doesn't make a unit right for your room. Size the purifier to your square footage first — our room-size guide covers the math — and treat CADR-per-dollar as the tiebreaker once you've sized it. Prices move; we'll refresh the table as they do.

The takeaway in one sentence: size the purifier to the room, then buy the best CADR-per-dollar that fits — which, more often than not, is a real room unit like the Winix 5510 or Coway AP-1512HH, not the cheapest box on the shelf. The full lineup lives on our air purifiers page.