Understanding CADR Ratings: What They Mean For Your Air Purifier Purchase

Alright, let's get straight to it. CADR stands for **Clean Air Delivery Rate**. In simple terms, it measures **how much clean, filtered air** an air purifier pumps out. It specifically looks at how well the machine removes three common types of airborne gunk.

This isn't just some random number the manufacturer made up. It's a standardized test developed by the Association of Home Appliance Manufacturers (AHAM). Their goal was to give us shoppers a fair way to compare different models side-by-side. The test measures how fast and effectively a purifier snatches three specific troublemakers out of the air:

• Tobacco Smoke
• Dust
• Pollen

You'll usually see the results as three numbers slapped on the box or listed in the specs, often looking something like **150 / 180 / 200**. Each number lines up with one of those pollutants (usually in the order Smoke / Dust / Pollen).

Here's the key takeaway: **the higher the CADR number, the faster the air purifier cleans the air** for that particular type of particle. Bigger number = more clean air per minute. Simple as that!

"Okay," you might be thinking, "why complicate things with three numbers?" Good question! It's because air purifiers aren't always equally good at grabbing different *sizes* of particles. The CADR test uses these three specific types of gunk because they cover a good range of the particle sizes floating around our homes:

So, which number should you focus on? It depends on what bugs you the most! If pollen season turns you into a sneezing mess, zoom in on the Pollen CADR. If you're dealing with smoke (from cooking, wildfires, or anything else), the Smoke CADR is your guy. For just general "get this dust out of my house" cleaning, the Dust CADR is a solid benchmark. Ideally, you want a purifier that scores reasonably well across the board.

Okay, let's get down to brass tacks. How do you actually *use* these CADR numbers to pick a purifier? This is where it gets super useful. AHAM came up with a handy rule of thumb to match the purifier's power (its CADR) to the size of your room. It's often called the **"Two-Thirds Rule"**:

**Let's break it down with an example:** Say your bedroom is a cozy 15 feet long by 10 feet wide.

• Room Area = 15 ft * 10 ft = 150 square feet
• Minimum Recommended Smoke CADR = 150 sq ft * (2/3) = 100

Boom! For that 150 sq ft bedroom, you should be looking for an air purifier with a Smoke CADR of **at least 100**. Easy peasy.

"But wait," you ask, "why use the Smoke number?" Great question! Since those tiny smoke particles are the hardest to trap, using the Smoke CADR ensures the purifier is strong enough to handle the toughest job. If it can clean smoke effectively, it'll likely breeze through capturing bigger dust and pollen particles.

This handy rule assumes you have standard 8-foot ceilings and aims to clean all the air in the room about five times per hour (we'll dive into that 'Air Changes per Hour' thing next). It's a fantastic starting point for making sure you don't buy a wimpy purifier for a big room, or a jet engine for a tiny closet!

Now, let's talk about another acronym you might see: **ACH**, which stands for **Air Changes per Hour**. While CADR is about the *volume* of clean air, ACH is about *frequency* – how many times per hour the purifier can filter *all* the air in your specific room.

Imagine you're cleaning a swimming pool:

• CADR is like the filter pump's power: How many gallons per minute it can clean.
• ACH is like how many times the *entire pool's water* goes through the filter each hour.

That 2/3 rule we just talked about gets you roughly 5 ACH, which is generally considered really good, especially if you've got allergies. But you might adjust your target based on your situation:

• Got Bad Allergies, Asthma, or Furry Friends? You'll want **4-5+ ACH**. Cleaning the air more often is key to keeping those triggers down. This might mean picking a purifier with a CADR rating a bit higher than the minimum 2/3 rule suggests for your room.
• Just Want Generally Fresher Air? **2-3 ACH** is probably fine if you don't have major breathing issues or pollutant sources.

**Heads up!** Some brands advertise a huge room size coverage, but it might be based on achieving only 1 or 2 ACH. That's not going to cut it if you need serious cleaning! Always look at the CADR number and think about the ACH you actually need for *your* situation. Don't be fooled by just the big square footage number on the box.

Now, CADR is awesome, but it's not a magic bullet that tells you everything. It's important to know what it *doesn't* measure:

• Smells & Fumes (Gases/VOCs): CADR is all about *particles* (like dust). It tells you zip, zero, nada about how well a purifier tackles smells, cooking fumes, chemical vapors (VOCs), or other gases. For that job, you absolutely need a different tool: a good **Activated Carbon filter**. Don't expect CADR to rate odor removal!
• Filter Quality & Lifespan: CADR measures the *result* (clean air output), not *how* it gets there. It doesn't tell you if the filter is a high-quality, long-lasting True HEPA or something flimsier. (Though, realistically, you need a decent HEPA filter to get good CADR numbers).
• How Loud It Is: The CADR test is done with the purifier blasting away on its highest setting. A machine might have amazing CADR numbers but sound like it's preparing for takeoff! You *must* check the noise levels (measured in decibels, dB) separately, especially the rating for its lowest 'sleep' setting if you plan to use it in a bedroom.
• How It Holds Up: CADR is a snapshot taken with brand-new filters. It doesn't predict how quickly those filters will get clogged in your dusty house or how much the performance drops off over months of use. (That's why changing filters is key!)
• Your Exact Allergy Trigger: The Dust and Pollen ratings give you a good idea, but they don't test for *every single type* of pollen or dander out there (like your specific cat's dander vs. general dust).

Bottom line: CADR is your go-to number for judging particle-cleaning speed and matching the purifier to your room. But don't stop there! Always check for that all-important Activated Carbon filter if you care about smells, look up the noise ratings, and consider other features you might want.

Alright, feeling a bit more confident about CADR? Let's put that knowledge into action. Here’s a simple game plan for using CADR when you're shopping:

1. Know Your Battlefield (Measure Your Room): Grab a tape measure and figure out the square footage (Length x Width) of the main room you want to purify.
2. Do the Quick Math (2/3 Rule): Take that square footage and multiply it by 0.67 (or just divide by 3 and multiply by 2 – same thing!). That number is the *minimum* Smoke CADR you should be looking for. Write it down!
3. Hunt for the Numbers: When looking at purifiers, find those CADR ratings (Smoke, Dust, Pollen). Check if the Smoke CADR is at least as high as the number you wrote down. Look for the AHAM Verifide seal – it's a good sign the numbers are legit.
4. Level Up if Needed (Think ACH): Got nasty allergies, a shedding pet, or live near a busy road? Don't just settle for the minimum CADR. Aim higher! Getting a unit with a stronger CADR for your room size means more Air Changes per Hour (ACH), which means cleaner air, faster.
5. Compare the Contenders: Once you've found a few models that fit your room size based on CADR, use the ratings to compare their particle-grabbing speed directly.
6. Remember the Rest: CADR is key, but it's not everything! Now check if it has that crucial Activated Carbon filter for smells, look up how loud it gets (dB!), see how much replacement filters cost (ouch!), and check for any other features you care about (like smart controls or timers).

Let's look at a real-world example. The popular Levoit Core 300 rocks a CADR around 141 CFM. Using our 2/3 rule backwards (141 divided by 0.67 is about 210), we see it's a great fit for rooms up to roughly 210-220 sq ft, especially if you want that sweet ~5 ACH for allergy relief.

LEVOIT Core 300 Air Purifier

Solid CADR of 141 CFM makes it great for bedrooms or offices up to ~219 sq ft (giving ~5 ACH). Includes True HEPA & Carbon filters.

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Need something beefier? The Levoit Vital 200S-P steps up with a CADR of 242 CFM. That makes it a solid choice for larger rooms around 360 sq ft (again, using the 2/3 rule), giving you strong cleaning power for living rooms or master bedrooms.

LEVOIT Vital 200S-P Smart Air Purifier

Higher CADR (242 CFM) tackles rooms up to ~360 sq ft effectively (~5 ACH). Bonus: washable pre-filter for pet hair, plus smart features.

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