THE NEW SYSTEM
Going forward, the judging criteria for our ranking list will be broken down into four distinct metrics: Performance, Features, Annual Cost, and Design & Build. We’ll explain each of these criteria in detail below, so keep reading if you’d like the full picture.
So, why the change?
From the beginning, we were already using this system for our rankings – just informally, and in a more “arbitrary” way. Specifying and breaking down the main criteria of our grading system helps us be more transparent about our internal process, as well as more consistent with Breathe Quality’s rankings.
It’s important to give you full information about how and why an air purifier was chosen as one of the best air purifiers. Since our lists are constantly updated, this system helps us keep track of older air purifiers we’ve tested over the years. After all, we’ve evaluated more than 500 air purifiers, and this data lets us share the most comprehensive summary of the best air purifiers.
We’ve been the trusted source for finding the best air purifiers since 2019, and our team has to say: a lot of rating systems kind of suck. Yes, we know that’s rich coming from a team that basically lives to review air purifiers. But here, we’d argue that their problem isn’t the concept – it’s the execution.
Disagreements about individual reviews aside, we’re not here to bash differing opinions. In the past, we followed the same approach as the top names – Wirecutter, CNET, and Consumer Reports. This article focuses purely on correcting rating and ranking systems, with real reasoning behind it, which will save you a lot of time in finding the best air purifiers.
Finally, we hope you enjoy our work and find the best air purifier for your home.
GRADES
For Ranking only.
S: Must try. Experience what the best has to offer.
A: While not at the top of the summit, Grade-A air purifiers are still the top and very good air purifiers to recommend. They would still be considered as some of the best by many.
B: While “B+” is still “very good”, the grade can essentially be described as the average in the ranking system.
C: Still average in the grand scheme of things, anywhere from “passable” to “good”.
D: They are “bad”. And “D-” means they’re just one step away to hell.
F: Simply, the failure.
WEIGHTING
For the most part, the overall ranking of an air purifier is weighted in favor of the lower of the four grades. However, we’ve devised a system that accounts for outliers with large deltas, though it still weighs heavily in the lower grade’s favor.
The system is essentially a 3-to-1 weighting scale, where only a full grade’s difference (3 sub-grades) results in a single sub-grade increase from the lower grade. Because we have four factors to consider, after finding the combined ranking of the first two grades, we then factor in the third. The fourth and least important factor, “Design & Build,” will only decrease the total ranking by one sub-grade when it’s a “D” or “F.”
An example is shown below:
[Performance]/[Features]/[Annual Cost] – [Design]= [Overall grade]
C/C+/C+ – S = C (1 sub-grade difference, no change. Also Design = “S”, no change).
C/B-/B- – S = C (2 sub-grade difference, no change)
C/B-/B – S = C+ (First, 2 sub-grade difference, no change. Then 3 sub-grade/1 whole grade difference, 1 sub-grade increase to lower-of-the-three)
C/B/A – S = B- (First, 3 sub-grade/1 whole grade difference, 1 sub-grade increase to lower-of-the-two equals “C+”. Then, 5 sub-grade difference, still 1 sub-grade increase).
C/B/A – D = C+ (The above situation with “D” design, so 1 grade degree).
This is also known as the Specialist’s Clause.
However, if any of the Performance, Features, or Annual Cost factors is graded an F, the Specialist’s Clause is void. That means, for instance, that if an air purifier’s Performance is graded an F, its overall ranking will be an F – even if it manages to score an S in Annual Cost.
Why not use an averaging system?
The problem with a direct averaging system (e.g., C-/C+ = C) is that the performance rating on the ranking list works on a “subjective log scale.” That is to say, the difference between C and C+ is much “higher” than the difference between A and A+. Thus, we don’t think it’s the right call to, for example, put a C-/C+ graded air purifier in the same league as one that scored a straight C.
At this point, we can confidently say that Breathe Quality’s ranking list is the most comprehensive one you can get right now. We must also note that, regardless, if you don’t agree with our weighting system, you’ll still be able to sort the ranking list by other factors.
A full up-to-date (as of 07/07/2026) list of air purifiers that have invoked the Specialist’s Clause is shown here.
Note Weight
The “note weight” section will be updated accordingly once we hear from you, our readers. But for now, we’ll take the time to explain what it is and why it could help with your purchase decision-making.
The Performance factor is based on our real-world tests. We grade each air purifier’s performance strictly based on its performance-to-price ratio, CADR rating per watt, and its actual results against the manufacturer’s suggested room size. An air purifier priced at less than $200 is expected to clean slower than, say, a $500 air purifier in the same room. Plus, while AHAM certification generally aligns with performance, we add one subgrade to AHAM-certified devices.
The Features factor has always been an important consideration for our team in choosing the best air purifiers. In fact, adding this factor to our list has pushed many air purifier manufacturers to make their devices “smarter.” While some features may not be core to an air purifier’s main function – for example, a “humidifier function” – we add one subgrade to air purifiers with such features, unless they’re already graded “S+.”
The Annual Cost factor is divided into annual power consumption and annual filter replacement costs. Again, while Energy Star ratings generally align with cost savings, we add one subgrade to Energy Star-certified devices.
The Design & Build factor is purely subjective at the moment. We believe that lower-cost air purifiers don’t need to be huge; more accurately, size should be proportional to power output. We also take note of build quality and unique design, but overall, this factor doesn’t affect the final grade very much.
FAQs
Can you give me an TLDR version of how you evaluate air purifiers?
We’re afraid you’re going to have to read through the whole article. This is already the TLDR version.
Why do you still use average numeric system in each air purifier review? Why don’t you simply update to the new ranking system?
Good point. At the moment, we don’t know how to implement Specialist’s Clause into any current ranking plugins. By adding an additional Price factor, we try to resemble our ranking system. However, it’s just nearly capture our ranking system. Nearly.
We recommend you to follow our air purifier ranking list for the most up-to-date grades.
