Xiaomi Smart Air Purifier 4 Compact – Trusted Review (2022)

Having followed the air purifier industry trends and doing reviews for several years, I have to say that I notice significant improvements and innovations with each new device released on the market.

For example, there is the Xiaomi Smart Air Purifier 4 Compact, which I have tested and will describe in this review, which is quite different from previous Xiaomi air purifiers, but mainly in design and some control principles.

Xiaomi Air Purifier 4 Compact - Review
Xiaomi 4 Compact air purifier on a small desk.

I like that it is much more automated than some of the previous models, relies much more on smart technologies, and retains the extremely high-quality filtration technology of its predecessors.

This small air purifier covers rooms up to 290 sq. ft., uses 3-stage filtration technology, and has a plenty of advanced options. I have to say that it was a real pleasure to test Xiaomi’s new model.

In fact, I must admit, after testing the Xiaomi Mi 3H air purifier, I haven’t tried any other model from this brand. Also, given that it is one of the most visited reviews, I don’t know why I haven’t tested more Xiaomi’s air purifiers before.

All in all, I believe that in the future, I will look into brands like Xiaomi. I will try out some other air purifiers from this brand, if nothing else, at least the 4th generation devices. Until then, sit back, read on and find out how good the Xiaomi 4 Compact air purifier is, how it performed in the tests and whether it’s worth buying.

Short on Time? Here’s My Short Summary of The Xiaomi 4 Compact!

  • The Xiaomi 4 Compact is a small air purifier designed for rooms up to 290 sq. ft.
  • This air purifier uses a 3-stage filtration technology consisting of a primary filter, a true HEPA filter, and an activated carbon filter.
  • The Xiaomi 4 Compact air purifier achieved fantastic results in performance tests and improved air quality by 94% in 194 sq. ft. room.
  • Xiaomi provides a 1-year warranty on this model.

Specifications

Check out the specifications of the Xiaomi Air Purifier 4 Compact in the table below.

Manufacturer Xiaomi
Model 4 Compact
Dimensions Φ8.6 x 14 inches (Φ22.0 x 35.5 cm)
Weight 4.8 lb (2.2 kg)
Filters Primary Filter, True HEPA Filter, and Activated Carbon Filter
Filter Longevity 6-12 months
Room Coverage 290 sq. ft.
Number of Working Modes 3 – Automatic Mode, Sleep Mode, and Manual Mode
Power Consumption 27W
Warranty 1-year

Setup and Installation

Although every air purifier requires some preparation before the first run, I have to say that I was surprised to find that the Xiaomi 4 Compact requires almost no preparation.

Given that the filter is in the device, ready to use, it is enough to just unpack the power adapter, plug it in, then plug the device in and turn it on. I would also mention placing the air purifier on a flat, hard surface and moving it at least 8 cm away from walls or other objects.

Never cover the appliance’s top while operating, as it can be easily damaged.

Design

My first thought when I took the Xiaomi 4 Compact air purifier in hand was, “Wow, how light is this air purifier.” Of course, that doesn’t mean it’s not good if it’s light, but it’s simply that the technology has advanced, the motor is of better quality, and there aren’t many metal parts inside the device, which in the end makes it lighter.

The second thing that came to mind after the first touch is that the Xiaomi 4 Compact reminds me a lot of the Smartmi P1 air purifier, which I also had the opportunity to test, which comes from Xiaomi’s sister company.

The plastic on this model is excellent, as is the build quality. Everything is simply in place. There are no separations and no foul edges. I like that the plastic is matt, so the device does not slip out of your hands.

Xiaomi Air Purifier 4 Compact - On the office desk
Xiaomi Air Purifier 4 Compact on the office desk.

The device is almost entirely white, except for the control panel, which is black. I like the fact that there are rubber ‘studs’ on the underside of the device to prevent the device from sliding on smooth surfaces. What I don’t like is that it doesn’t have a carrying handle, or rather, some kind of carrying strap, as is the case with the aforementioned Smartmi P1. However, the Xiaomi is very light, and you’ll have no problem moving it from room to room, so we can neglect that drawback.

To be honest, I like that Xiaomi has released a cylindrical model because I find this design very practical, besides looking nice. Of course, I cannot pass over the fact that Levoit is the company most responsible for this design innovation on the market. After the famous Levoit Core 300, many manufacturers started to produce air purifiers with a similar appearance.

Let me return to the Xiaomi story and conclude that this is a stylish and modern air purifier that, I am sure, fits into almost any environment.

Controls

The Xiaomi 4 Compact has control panel on the top of the device, which is consisting of touch buttons and LED indicators.

The buttons on the device are the Power button, the Light adjustment button, and the Mode switch button.

Pressing the Mode Switch button activates the indicators located in the center of the device. Those are three different indicators, the first is a heart-shaped indicator indicating manual mode, the second is a crescent-shaped indicator showing sleep mode, and the last is A letter-shaped indicator indicating the auto mode. Just below these indicators are a child lock indicator, a Wi-Fi indicator, and a filter reset indicator.

Xiaomi Air Purifier 4 Compact - Control Panel
Xiaomi 4 Compact control panel.

The touch buttons are precise and sufficiently sensitive to pressure, while the LED indicators are highly visible and well-spaced.

In addition to controlling the device via the control panel, there is also the option of handling it via the Mi Home App, which, in addition to the controls mentioned above, offers the possibility of additional advanced controls such as an advanced timer or manual mode.

Airflow

As I mentioned, the Xiaomi 4 Compact is cylindrical in shape, with the cilndircal filter located inside the bottom part of the device. The air inlets are located at the bottom of the unit arranged on all sides. When the air is drawn through these inlets, it is filtered and exits through the grilles on the top side.

Size and Dimensions

The air purifier weighs 4.8 lb (2.2 kg). The device dimensions are: Φ8.6 x 14 inches (Φ22.0 x 35.5 cm).

The Xiaomi 4 Compact is not a heavy air purifier. Although it does not have a carrying handle, due to its compactness, I think moving it from room to room won’t be a problem.

What’s in the box?

In the shipping package you will receive a Xiaomi Air Purifier 4 Compact, 3-in-1 filter (pre-installed),  power adapter, and user manual. Fortunately, this air purifier doesn’t require any complicated preparation, which means you’ll be able to start using the device immediately after unpacking it.

Features

Xiaomi is a company known for innovation, smart options, and accessories years ahead of some other manufacturers. This is the situation with air purifiers, which is why the Xiaomi 4 Compact is equipped with some advanced options and many additions that will make the daily use of the device easier and help improve the quality of filtration.

Below, I have described in detail all the most important features of this air purifier. I have also listed some tricks and tips to pay attention to when using the Xiaomi 4 Compact.

Air Quality Sensor and Indicator

The Xiaomi 4 Compact uses an IR (infrared) particulate matter sensor that detects the amount of PM 2.5 in real-time. The sensor is located on the back of the device. It has a separate motor that runs even when the device is in standby mode, meaning it monitors the current air quality at all times.

Xiaomi Air Purifier 4 Compact - Laser particle sensor
Xiaomi 4 Compact air quality sensor.

The current air quality can be monitored directly on the device by an LED indicator that lights up in different color depending on the concentration of PM2.5 in the air. Below is a table explaining how much PM2.5 is in the air depending on the indicator’s color.

In addition, you can check the current indoor air quality and the amount of PM2.5 in real-time at any time via the smartphone app. In short, it is one precise sensor that is also very useful and makes it much easier to automate the device and use it daily.

Please note that the air quality sensor should be cleaned with a dry cotton swab every few months to maintain the sensor’s high accuracy.

Automatic Mode

Automatic mode is another option that works in combination with the air quality sensor.

Basically, when the Xiaomi 4 Compact is switched to Auto mode, the device will change the fan speed according to the current air quality in the room. This can be very useful if you want to turn the device on once and let it do all the work.

As this air purifier uses a high-quality IR (infrared) air quality sensor, rest assured that the combination of the automatic mode and this sensor will keep the air quality in your room at the highest level.

Sleep Mode

Sleep mode is another additional mode on this device. As the name suggests, this mode is designed and recommended to be switched on when using the air purifier in the bedroom

Why in the bedroom?

Well, because when in sleep mode, the air purifier reduces the fan speed to the lowest, which is ideal for the bedroom, especially if you are sleepy.

Xiaomi Air Purifier 4 Compact - In my bedroom
Xiaomi 4 Compact in my bedroom.
When using the sleep option, I recommend dimming the LED indicators on the control panel, as the extra lighting can make it difficult to sleep.

Manual Mode

This mode is characterized by the fact that it can only be controled via the smartphone app. This means that to use this mode smoothly, you need to connect the air purifier to the Mi Home smart app, which I will explain how to do below.

When you switch to this mode on the control panel, it works based on the custom settings you have previously set in the smart app.

Personally, I use this option by selecting the manual mode in the smart app to the highest possible speed. Then when I want to set the air purifier to run at max speed for a while, I simply switch to manual mode. To be honest, I don’t think it would be bad if the device had the option to change the fan speed directly on the control panel because sometimes, when using this air purifier, I feel like I miss it.

Light Adjustment

This is a handy option if you plan to use the device in the bedroom. Namely, the Light Adjustment button operation is very simple; with each button press, the brightness indicators on the control panel change completely, to the point where you can dim them completely.

However, remember that the indicator on the Power Button can’t be completely dimmed, but it can dim enough not to disturb you even in a completely dark room.

Filter Exhaustion Indicator

This is a very useful option that comes in two forms. When you connect the air purifier to a smartphone app, you can monitor the current filter wear at almost any time.

There’s an indicator on the dashboard that lights up when it’s time to change the filter. It is important to note that the filters on this device last approximately 6-12 months, which means that the filter wear indicator will light up 1-2 times a year.

Warranty

Xiaomi is not very generous regarding the warranty, which is why it only gives a 1-year warranty for this model.

Given that Xiaomi is available across different stores, the warranty may vary from store to store, so in some places, you get a longer warranty, at least 2 years. So keep this in mind before buying.

Xiaomi 4 Compact Video Review

Check out in the video above all the things you should know about the Xiaomi Smart Air Purifier 4 Compact. See it in action and how it behaves in a room while providing fresh, clean air.

Mi Home app

Like almost all other devices in the Xiaomi ecosystem, the Xiaomi 4 Compact can be connected to the Mi Home App. The Mi Home is a universal app that connects many different devices, allowing you to control them from one place and, of course, helping make your home smart. This is one reason why this app works perfectly and almost without issues, which is not very common with smart air purifier apps.

Xiaomi 4 Compact and Xiaomi Mi 3H side by side
Xiaomi 4 Compact and Xiaomi Mi 3H side by side.

I must point out that, in addition to this model, I have also tested the Xiaomi Mi 3H, which also works without issues and connects to the smart app in a few simple steps.

Using the app is straightforward, especially if you are familiar with smartphones. Everything is very well designed and user friendly.

In the following headings, I will describe the essential functions this app opens to you after connecting it with the Xiaomi 4 Compact.

As the app can sometimes be challenging to connect to and use, if you encounter a problem, please leave a comment in the comment box below, and I will get back to you as soon as possible. I’ll reply to you as soon as I receive your comment and respond as quickly as possible.

Installation and Adding Device

Xiaomi 4 Compact - Installation and Adding Device
Installation and adding device to the app.

You must take several steps before connecting your device to the Mi Home smart app. First, you need to download the app from the Android or iOS app store and install it on your smartphone. Then create an account on Xiaomi with a valid email address, and once you have created an account, log in to the system.

On the first screen, you will notice that no devices are added or connected to your app.

So, simply press the “Add Device” button and follow the on-screen steps to connect your Xiaomi 4 Compact to the Mi Home app. As for the process itself, it’s straightforward, and I didn’t encounter any problems, even though I connected/disconnected the air purifier and the app several times.

In short, I am delighted with the ease of using the Mi Home App. However, remember that you must follow the on-screen instructions as closely as possible and check and confirm that you are not using a 5G router, as you will then not be able to connect to the app and the WiFi.

Main Dashboard

Xiaomi 4 Compact - Main Dashboard
Main screen, controls, and indicators.

After a successful pairing, you will see that the Xiaomi 4 Compact is listed in your device list.

Now click on the device to open the main control panel, through which you control the entire device. Right from the top, you will see information about the current air quality in the room.

Bellow, you will see buttons used to switching between Auto, Sleep, and Manual operating modes. Note that pressing Manual will open a slider to adjust the room size, based on which the device adjusts the fan speed.

Under the buttons, there are some more options. First, there is the current filter wear, then the advanced timer button, the light adjustment button, the child lock, turning the buttons’ beep on/off, and scenes.

To be honest, when it comes to Scenes, I am not very pleased, and this option seems unfinished. Namely, on the Xiaomi Mi 3H, I had the opportunity via Scenes to set the air purifier on or off according to the current air quality, but on this model, this is not possible, so I have the impression that the option is unfinished. As for the other options available via the smartphone app, I have almost no complaints.

Connecting to the Mi Home App opens up the voice control posibility via Amazon Alexa and Google Assistant.

Room Coverage and CADR

Xiaomi recommends using this air purifier in a room of up to 290 sq. ft. However, considering the AHAM standards, this air purifier would be best used in rooms up to 213 sq. ft. because Xiaomi cleans the air 4.8 times in an hour in a room of these dimensions.

The CADR of the Xiaomi 4 Compact is 230m³/h, which I think is solid for such a small air purifier. Based on this, we can easily calculate and conclude that this air purifier in a room of 520 sq. ft. can clean the air 2 times in one hour. I think that this small, stylish air purifier will fit into many rooms, but most of all, in a small living room, a small bedroom, a kitchen, or an office.

In short, based on the tests taken out, I don’t recommend using this air purifier in rooms much larger than 290 sq. ft.

With advanced smart technology and manual mode, you’ll be able to easily adapt the Xiaomi 4 Compact to a room of certain dimensions.

Filtration Technology

The Xiaomi Air Purifier 4 Compact uses, so to speak, standard 3-stage filtration technology consisting of a primary filter, a True HEPA filter, and an activated carbon filter. The filter is cylindrical in shape, hollow through the middle, located on the underside of the unit, and takes up almost half of the device.

Xiaomi Air Purifier 4 Compact - 3-in-1 True HEPA filter
Xiaomi Air Purifier 4 Compact – 3-in-1 True HEPA filter.

I don’t have much to say about the filter itself, as cylindrical air purifiers have become somewhat of a standard, and most of them look exactly the same, but the filtration technology and the accompanying technology are different.

As for the overall quality of the filter on the Xiaomi 4 Compact, I have to say that I am delighted with it and that it is a highly efficient filter, which contributed to the excellent results in the performance tests.

Primary Filter

The primary filter is the first stage of filtration. Its main role is to trap large particles in the air, including pet hair, pollen, and dust, thus extending the life of the True HEPA filter and, of course, improving the quality of filtration. It is essentially a nylon mesh filter glued to the True HEPA filter that easily catches all large particles.

I think the most significant benefit of this filter will be noticed by people who have pets (because of the amount of hair that will get caught on the filter) or a lot of dust in the room. I would like to point out that as this filter gets dirty very quickly, I recommend cleaning it regularly with a dry cloth or vacuuming it with a vacuum cleaner.

True HEPA Filter

The True HEPA filter is the second stage and most basic level of filtration. This filter traps 99.97% of particles as small as 0.3 microns, such as dust, pollen, smoke, and pet odors. Xiaomi’s filter uses fusion-blown PP fibers with electrostatic technology. By increasing the spacing between the fibers, a greater volume of air can pass through the filter.

Activated Carbon Filter

The activated carbon filter is the final stage of filtration and is designed to neutralize odors in the room. I like the fact that this filter is a pellet-based, so its efficiency is much higher. Still, I would also point out that I would have liked to see more carbon pelets inside, which would have increased the efficiency and durability of the filter itself.

How do I replace the Xiaomi 4 Compact filter?

The Xiaomi Air Purifier 4 Compact does not use washable filters, so you need to change them occasionally. This period is, on average, between 6-12 months, depending on how actively and in what environment you use the air purifier.

The good thing is that the machine will let you know when it’s time to change the filter. The best way to see this is via the Mi Home App, where you can monitor the percentage of wear on the filter every second.

Noise Test

Before I move to the test results, I must highlight that this is one of the best-quality motors I have tested so far. Although louder at certain speeds, the sound it produces is so pleasant and smooth that there is no humming, popping, or other sounds that could disturb or irritate you.

The Xiaomi Air Purifier 4 Compact uses an efficient brushless DC motor that has no friction with the carbon brushes, making it quieter and more energy efficient.

Xiaomi Air Purifier 4 Compact - Noise test
I used a special tool to measure the Xiaomi 4 Compact noise levels.

Given that the Xiaomi 4 Compact does not have a fan speed switching option by default, and to avoid confusion, I tested how loud this air purifier is in sleep mode and at maximum speed. I think this is enough to determine the loudness rating of this model.

Interestingly, in sleep mode, this air purifier is very quiet and produces a sound of only 41.3 dBA. So, you can use it in a bedroom or a similar room without any problems.

At the max speed the Xiaomi produces a sound of 60.4 dBA, much lower than some other competing air purifiers in the same class.

Speed Value (dBA)
Sleep Mode 41.3 dBA
Max Speed 60.4 dBA

Overall, I conclude that this is a very quiet air purifier and generally one of the quietest I have tested, which is especially important if this is a crucial feature for you when choosing an air purifier.

Performance Tests

The Xiaomi Air Purifier 4 Compact is a small air purifier that covers rooms up to 290 sq. ft. This coverage is a manufacturer’s suggestion. I have taken it as a reference, and based on this, I have taken out tests in rooms of approximate dimensions, the results of which you will find below.

Xiaomi Air Purifier 4 Compact - Performance test
I used the Temtop laser particle meter to measure this air purifier’s performance.

In addition to the tests I have presented below, I must say that I would have liked the filter to contain a few more carbon pellets, as I think that would have been much more effective in neutralizing odors and smoke. I am not saying that it is not efficient now, but I believe that the quality of the carbon filter on this machine is far behind that of the True HEPA filter, which is of top quality.

Overall, I am very satisfied with this device’s performance and the results it has shown in all the tests carried out.

194 sq. ft. Room Test

In the first test, in a room of 194 sq. ft., slightly smaller than the recommended dimensions, the Xiaomi 4 Compact performed exceptionally well, improving air quality by approximately 94% in just 60 minutes, working at maximum speed.

# Starting Baseline After 60min
PM 2.5 95.5 5.2
PM 10 133.8 7.3
Particles 138614 7617
AQI 125 7

This is an excellent result and proof that Xiaomi is a serious competitor to some similar air purifiers in the class.

320 sq. ft. Room Test

In the second test, this time in room 320 sq. ft., larger than the recommended dimensions, Xiaomi also achieved excellent results, albeit a shade weaker than in the previous test. In 60 minutes of operation at maximum speed, this air purifier improved air quality by around 91%

# Starting Baseline After 60min
PM 2.5 98.1 9
PM 10 137.4 12.6
Particles 142338 13148
AQI 128 12

Considering the room’s size, we can conclude that this is also an excellent result and that in rooms slightly larger than the recommended dimensions, the Xiaomi will do the job.

Operating Costs

When it comes to the operating costs, I would first add the power consumption and say that the Xiaomi 4 Compact uses a motor with a power of only 27W, which is more than reasonable, especially considering the airflow that this device has.

Xiaomi Air Purifier 4 Compact - Power usage
Xiaomi 4 Compact motor.

Taking into account that, based on the tests I have carried out, this air purifier consumes 24.2W at maximum speed, this means that if you were to use this device at full speed for one month, 24 hours a day, your electricity bill would increase by about $2.1. This is a minimal cost, especially considering that we will not be using the device at max speed all the time.

Speed Power Usage (W)
Standby 1.8W
Sleep Mode 2.6W
Max Speed 24.2W

In addition to the electricity cost, there is the cost of changing the filter, which needs to be changed on average 1-2 times a year, and which fortunately is not very expensive. This means that the Xiaomi Air Purifier 4 Compact is essentially a cheap air purifier that is also very affordable for annual maintenance.

FAQ on Xiaomi 4 Compact

Does the Xiaomi Air Purifier 4 Compact produce ozone?

No, it doesn’t. This air purifier does not have an ionizer or other filter technology that can produce ozone. It is also CARB certified, which indicates that it is safe to use.

How often should I change the filters on this device?

Xiaomi requires filter changes on average between 6-12 months, specifically when the filter reset indicator on the control panel lights up.

What is the warranty on the Xiaomi 4 Compact?

This model comes with a 1-year warranty.

Is the Xiaomi air purifier effective?

Of course, it is. This air purifier uses a high-performance True HEPA filter that traps particles down to 0.3 microns in size. This means it neutralizes pollen, smoke, dust, and similar particles from the air without much effort.

Pros and Cons

To revise, here are the advantages and disadvantages of the Xiaomi 4 Compact:

Pros

  • Air quality sensor
  • Air quality indicator
  • Automatic mode
  • 3-stage filtration technology
  • Mi Home Smart App
  • Ultra-low power consumption
  • Excellent performance
  • Not very loud when working
  • Excellent price/quality ratio
  • Long-lasting filters
  • Easy to maintain
  • Easy to use

Cons

  • It would be good if the warranty was longer
  • Lack of some controls on the control panel
  • The charcoal filter could have a few more carbon pellets

Final Thoughts

After extremely detailed testing and use, I conclude that the Xiaomi Smart Air Purifier 4 Compact is a very interesting, innovative, and, above all, very efficient air purifier that surprised me positively in all tests.

This small air purifier is best used in rooms up to 290 sq. ft., it scores fantastic results in performance tests, runs quietly, is very affordable to maintain, and has many advanced options. That said, I believe that the above, as well as many other reasons, are pretty enough to give the Xiaomi 4 Compact my absolute recommendation for purchase.

If you have any further questions about this device, please comment in the comment box below, and I will get back to you as soon as possible.

9.4

SCORE

Review Breakdown

Performance

9.4

Noise

9.6

Operating cost

9.2

Value for money

9.4

Ease of use

9.6

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