If you’re in the market for an air filter, chances are you’ve come across the acronym “CADR”. It stands for Clean Air Delivery Rate and, in short, is a quick and handy reference for how well a unit eliminates tobacco smoke, dust and pollen. Scaled from 1-450, the closer to 450, the more effective the purifier is at quickly and consistently removing said particle from a roughly 1,000 cubic foot room. The whole point of CADR was to inform consumers on the overall effectiveness of a unit. Back in the day, units with a tiny HEPA filter and/or fan could make all sorts of claims. With CADR, the actual volume of air treated standardizes everything and those misleading units tend to score horribly low. If you’re thirsty for more, let’s dive on in…

The CADR Seal

The most recent version of the CADR seal is pictured here (you may run into older versions of the seal on packaging, etc, but the key data is the same). As you can see, there are 2 main components: the suggested closed room size and the actual CADR scores. The closed room size is the suggested room area given the CADR numbers (it’s generally calculated based on a complicated equation involving the smoke CADR; as a rough guide though, the closed room size will never be larger than 2/3 of the smoke CADR). The CADR scores are intentionally listed from left to right as follows: tobacco smoke, dust and pollen. They’re ordered based on the smallest particulate (and most harmful to your health: cigarette smoke) to the largest (pollen). Here’s a bit more on each…


Particles Tested

Tobacco Smoke: Probably one of the most difficult things to get rid of (especially when it clings to fabric), tobacco smoke tends to linger for days/weeks when not properly treated. One of the smallest particulates you’ll find in the air, it takes an efficient HEPA filter series and a powerful fan to re-circulate the air enough to thoroughly tackle smoke molecules. With respect to CADR, the tobacco smoke number will always be the lowest of the bunch (or equal) and anything above 200 is considered above average.
Dust: this is the catch-all for everything from common household dust to any particulate that enters your home from the outside (fine dirt, random pollutants, etc.). Any value over 250 tends to be good, with a handful of units on the market exceeding 400 (they tend to have a price tag that’s north $750).
Pollen: Of the three, pollen can cause the most immediate discomfort…especially to allergy sufferers. Once it triggers a histamine response, it’s usually hours or days of continuous tearing, sneezing and general malaise. If that’s you and its allergy season, be sure to check this rating before just about anything else.

Recommended Purifiers based on CADR

CADR provides a ton of consumer value (especially if you’re in a hurry), so it’s no surprise that a lot of folks rely on this spec more than any other. So, everything else being equal, here are the CADR units we recommend most often, based on budget:

Sub-$250: at just $199, the Alen BreatheSmart clocks in at a CADR of 256, 276, 300. Nearly every other model in its price range has a CADR of well under 200, so the BreatheSmart continues to offer a ton of tangible and verifiable value.

$250-$1000: probably the most powerful, yet still affordable unit available to consumers, the IQAir HealthPro Plus boasts a CADR of 450, 450, 450 (maxed out the test). At a price tag of about $850, you won’t find a more powerful unit under $1,000.

Wrapping Up

There are plenty of things to consider when you’re looking for an air filter. Cost, room size, durability, brand value, replacement filter cost, etc. Of the entire lot, Clean Air Delivery Rate should rank right up near the top. If nothing else, consider using it as a tie-breaker if you can’t decide between two similar units. The CADR numbers don’t lie and the additional filtering power will go a LONG way over the life of a typical unit.