The thing is that air purifiers usually don’t have a large CADR and aren’t designed for large rooms. However, there are many devices on the market with a CADR ideal for medium to large-sized rooms (up to around 350 sq. ft., or slightly larger).

In these cases, based on my experience and opinion, it’s better to use one device for the following reasons:

• You will hardly notice any difference in performance if you use two smaller devices;
• Replacement filter costs can be significantly higher because small air purifiers tend to need replacement more frequently, last shorter, and in this case, multiply everything with two;
• Energy costs can also be higher when using two devices;
• It’s simply easier to manage one device rather than two.

Again, we can discuss this further using examples of specific devices available on the market. Just let me know which ones you’re considering.

“I would recommend using just one device that’s capable of exchanging the air in the room about five times per hour.”
Could you please explain why, considering the price for 2 smaller ones is the same as 1 larger one?

Hi Oleksandr,

Thanks for the great question!

There are many variables missing here, especially since not every large air purifier performs identically (well).

If the room is smaller, let’s say around 350 sq. ft. (33 m²), I would recommend using just one device that’s capable of exchanging the air in the room about five times per hour.

However, if the room you plan to use it in is much larger than 350 sq. ft. (33 m²), I would consider buying two air purifiers and placing them in different spots in the room or home.

I have a question: let’s say there are two different types of purifiers: “A” purifier has 260m3/h, and “B” has 520m3/h.

“A” costs 100$, “B” costs 200$.

There is no difference in filters or other parts. What is better to buy? 2 “A” purifiers or 1 “B”?

I would recommend the Xiaomi 4 Lite. It’s large enough for your apartment and will capture airborne dust and mold particles, so you should notice less dust in the air.

Two Xiaomi 4 Compacts would also do the job, but I don’t think it’s necessary to have two air purifiers in such a small place.

Looking forward to your response! Thank you!

Hi, I compared these two some time ago: check it here.

I would go with Xiaomi; even though there aren’t too many differences between the two, I just prefer Xiaomi’s smart features. The performance, noise level, and operating costs are almost identical.

You can always read my in-depth comparison of the Xiaomi 4 Compact and the Philips Series 800.

It does.

Thanks in advance!

Hi Alex,

That is definitely something I will consider doing, as it would be a great metric when updating/improving the guide for air purifiers in the bedroom.

In fact, effectiveness at the lowest settings would be a huge point of difference between different purifiers. I know, for example, that I would buy the one with the most effective night mode setting.

I have seen anecdotal reports on Amazon.com that this purifier did next to no purifying during night mode (he used smoke from a match or candle to see if it got sucked in) but a rigorous test like you can provide would be very important. Thank you!