Best For
- Great purification performance, reduce PM2.5 to 0.3 within 2 hours
- Touch display and app connectivity
- Auto and sleep mode
Considerations
- Tall air purifier, isn’t easy to move around
- Small coverage area compared to the size of the system.
Our Verdict
The Xiaomi Smart Air Purifier Pro 4 has a modern design with great usability features. It has an auto mode which adjusts based off of readings from the internal sensor and a sleep mode for silent air purification. The Pro 4 was able to remove 97.6% of particles in our tests and reduce the PM2.5 to 0.4. This solid performance is coupled with great features, which would be a great fit for any home.
Filter Type: Pre-Filter, Proprietary (non-HEPA) filter, Activated Carbon, Negative Ion Filter
Coverage Area: 645 sq. ft.
CADR: 500 CFM
In This Review
Purification Performance | Ozone Test | Filters | Coverage | Build Quality | Noise Test | Usability | Maintenance | Size | Specs | Product Evolution | Comparison | FAQs
Performance Summary
At Modern Castle we test 11 different factors that impact the performance, build quality, and usability of the air purifier. Below is a complete list of our testing categories and their performance.
| Test Type | Test Data |
|---|---|
| PM2.5 (2 hour test) | 0.3 ppm |
| PM10 (2 hour test) | 0.4 ppm |
| Particles (2 hour test) | 59 |
| AQI (2 hour test) | 1 |
| Ozone Detected | 0.0 ppm |
| Filter Type | Carbon, Pre-Filter, Ionizer |
| Coverage Area | 646 sq. ft. (60 sq. m.) |
| CADR | 500 CFM |
| Max Wind Speed | 12.1 mph (19.5 kph) |
| Noise Test | 57.8 dB |
Purification Performance
To test the purification performance of the Xiaomi Smart Pro 4, we placed it in a medium-sized room in our office (~14’ x 10`). Next, we lit incense to introduce smoke and other particulates into the air for 30 seconds. After, we use a professional air quality detector to take a measurement of the smoke filled air.
Next, we run the air purifier on the highest fan speed for 2 hours, taking measurements of the air quality at the one hour mark and the end of the test. Here is what we found:
| Performance Metric | Starting Measurement | After 1 Hour | After 2 Hours |
|---|---|---|---|
| PM2.5 | 24.8 ppm | 0.4 ppm | 0.3 ppm |
| PM10 | 43.5 ppm | 0.6 ppm | 0.4 ppm |
| Particles | 3649 | 86 | 59 |
| AQI | 77 | 1 | 1 |
The Xiaomi Smart Pro 4 showcased good results reducing PM2.5 down to 0.3 and PM10 down to 0.4 after the 2 hour test. By comparison the average air purifier we test is able to reduce PM2.5 down to 0.2 and PM10 to 0.3. The Smart Pro 4 had slightly worse performance, but still within healthy breathing levels.
Below, we’ve included information on the testing criteria and what defines good vs. bad air quality. Simply, the lower the numbers the better.
This is somewhat surprising considering the 1 hour test results. After 1 hour, the Smart Pro 4 reduced PM2.5 to 0.4, only 0.1 more than the 2 hour test results. Still, both the 1 hour and 2 hour results are well with healthy breathing levels.
Ozone Test
With most air purifiers ozone generation isn’t an issue. That said, some that use negative ion generators have the potential to create ozone. To test this, we run the Xiaomi Smart Air Purifier Pro 4, letting it run for 1 hour and measure the levels of ozone before and after with an ozone meter device.
Pre-test Ozone
0.0 ppm
Post-test Ozone
0.0 ppm
In our ozone tests, the Xiaomi Smart Air Purifier Pro 4 generated 0 ppm. This is consistent with all air purifiers we have tested to date.
Filters
The Xiaomi Smart Pro 4 comes with 3 different air filters and an always on negative air ionizer.
Proprietary Non-HEPA Filter – The filter does the majority of the work capturing particles as small as 0.3 microns. Notably, the filter is not a HEPA filter. It is a proprietary design.
Activated Carbon – These filters focus on capturing VOCs, odors, and gasses that the pre-filter and the HEPA filter miss.
Pre-filter – These air filters are designed to catch larger particulates in the air before the main filters. It’s best designed to catch human/animal hair, lint, or large dust particles.
Ionizer – This feature releases negatively charged particles into your environment, forcing extremely small airborne particles to clump together and fall to the floor. This feature can be turned on or off.
Coverage
The Xiaomi Smart Air Purifier Pro 4 has a coverage area of 645 sq. ft. It is best suited for small to medium sized homes.
Coverage Area
646 sq. ft.
CADR
500 CFM
For the size of this air purifier, we would expect the coverage to be higher than just 646 sq. ft. Compared to some of the other full sized models we have tested, they typically get closer to the 1000 sq. ft. and above. The Pro 4 was 80.6 sq. ft. below our coverage testing area of 726.6 sq. ft.
In addition, the Smart Pro 4 has a CADR of 500 CFM which, according to Xiaomi moves 8,330 L of clean air every minute.
Wind Speed Test
Our wind speed test uses an anemometer placed directly on the air vents of the Xiaomi Smart Air Purifier Pro 4 to measure the fan speeds in miles per hour. We run it on the lowest and highest fan speeds and record the speed of the air coming out of the device.
Minimum Wind Speed
0.2 mph
Maximum Wind Speed
12.1 mph
The maximum wind speed for the Xiaomi Pro 4 was 12.1 mpg, which is 0.5 mph above our testing average.
However, the Pro 4 had an impressively low minimum wind speed of 0.2 mph, being well below our testing average of 3.64 mph.
Build Quality Test
Our build quality test is a subjective test where we examine and assess the major material and design components of the air purifier. Specifically, we are looking for build and design issues that are more likely to break and/or be difficult to use.
The build quality of the Xiaomi Pro 4 received excellent scores in our assessment. Like most air purifiers, the Xiaomi is built out of plastic. While handling and moving the air purifier around the testing lab, it felt sturdy and well assembled.
| Part | Build Quality |
|---|---|
| Overall | Excellent |
| Body | Excellent |
| Fan | Very Good |
| Filters | Excellent |
| Controls | Excellent |
| Display | Excellent |
| Remote | Excellent |
| Wheels | n/a |
Noise Test
To determine the level of noise that the Xiaomi Smart Air Purifier Pro 4 creates we use a sound meter and measure the decibel levels on both the lowest and highest fan speeds. In addition, we measure the ambient noise levels of the room as a baseline comparison.
Ambient Noise
44.5 dB
Min Noise
44.5 dB
Max Noise
57.8 dB
When placed on the highest setting, The Pro 4 had a measured decibel reading of 57.8 dB, which is 4.25 dB below our testing average of 62.08 dB. On its lowest setting, it had an impressive 44.5 dB reading, which was the same as our ambient measurements in the lab.
Usability
The Xiaomi Smart Air Purifier Pro 4 is called smart for a reason. It’s designed to improve usability using its internal sensors, a touch display, and app connectivity.
Setup
Setting up the device is as simple as unwrapping the product and plugging it in. Please note: the filter will come packaged inside the device. Make sure to remove the packaging surrounding the filter before plugging in the Pro 4 and turning it on.
Once the device is powered, it can start cleaning the surrounding air. However, if you want access to additional smart features, you will need to connect the device to the Mi Home app. Simply download the app and follow the in-app instructions to connect the Pro 4.
Controls & Display
When controlling the Xiaomi Smart Air Purifier Pro 4 you have three options: Touch panel, Mi Home app, and your voice.
With the touch display, you have two touch buttons that can turn on the device and cycle through the various modes. Here are the modes available with the Pro
With the touch display, you have two touch buttons that can turn on the device and cycle through the various modes. Here are the modes available with the Pro 4:
- Auto mode
- Sleep mode
- Manual mode
- Low speed
- Medium speed
- Max speed
Wireless Controls
To remotely control the device, you can use the Mi Home app. With the app, you get access to the same controls on the display, and other features like a timer or custom schedule. Additionally, you can check in real-time the current air quality information from the device. Through the Mi Home app you can connect your device to Amazon Alexa or Google Assistant, to control the device with your voice.
In The Box
- Xiaomi Smart Air Purifier Pro 4
- Proprietary (non-HEPA) filter
- User manual
- Power Cable
Maintenance
The Xiaomi Smart Air Purifier Pro 4 has an estimated yearly maintenance cost of $50. The following are the major maintenance tasks for the Xiaomi Smart Air Purifier Pro 4.
| Task | Description | Est. Annual Cost |
|---|---|---|
| HEPA Filter | Replace every 12 months | $50 (Main Filter) |
| Carbon Filter | Remove tangles and any obstructions | $50 (Main Filter) |
| Pre Filter | Wash as needed | $0 |
| Sensors | Wipe clean as needed | $0 |
Size & Dimensions
In terms of size, I would consider the Xiaomi Pro 4 a medium-sized air purifier. It has a simple and tall design, with a modern aesthetic.
| Attribute | Measurement |
|---|---|
| Height | 26.8″ (68.1 cm) |
| Length | 0.0″ (0.0 cm) |
| Width | 10.8″ (27.4 cm) |
| Weight | 15.0 lbs. (6.8 kg) |
Specifications
The following table details the product specifications according to the manufacturer.
| Manufacturer Specifications | |
|---|---|
| Manufacturer | Xiaomi |
| Model | Smart Air Purifier Pro 4 |
| Height | 26.8″ (68.1 cm) |
| Length | 0.0″ (0.0 cm) |
| Width | 10.8″ (27.4 cm) |
| Weight | 15.0 lbs. (6.8 kg) |
| Filter | Carbon, Pre-Filter, Ionizer |
| Noise Levels | 58 dB (max) |
| Coverage Area | 646 sq. ft. |
| CADR | 500 CFM |
| Wi-Fi Compatible | Yes |
| Warranty | 1 year |
| Price | Check Price |
Product Evolution
Xiaomi does have a line of smart home fan systems ranging from purifiers, fans, and humidifiers. The Pro 4 is the only full size air purification system offered by Xiaomi. The Xiaomi Smart 4 Compact however, is the smaller version of the Pro 4.
How does Xiaomi Smart Air Purifier Pro 4 compare?
Below is a complete list of our air purifier tests and critical product data compared side by side to the average based on all of our air purifier tests to date.
| Test Type | Test Data | Avg. Data |
|---|---|---|
| PM2.5 (2 hours) | 0.3 ppm | 0.2 ppm |
| PM10 (2 hours) | 0.4 ppm | 0.3 ppm |
| Particles (2 hours) | 59 | 45 |
| AQI (2 hours) | 1 | 1 |
| Ozone Detected | 0.0 ppm | 0.0 ppm |
| Filter Types | Carbon, Pre-Filter, Ionizer | n/a |
| Coverage Area | 646 sq. ft. | 727 sq. ft. |
| CADR | 500 CFM | 289 CFM |
| Max Wind Speed | 12.1 mph | 12.1 mph |
| Noise Test | 57.8 dB | 61.8 dB |
The Xiaomi Pro 4 showcased slightly worse than average purification performance reducing PM2.5 down to 0.3, while the average air purifier we’ve tested to date reduces PM2.5 down to 0.2.
In addition, the coverage area is less than 80.6 sq. ft. less than the testing average of 726.6 sq. ft. This is neither better or worse, but depends on your specific needs.
Finally, the Smart Pro 4 tends to run quieter than the average air purifier we test, creating 4.25 dB less noise than our testing average of 61.84.
Other Air Purifiers to Consider
Create simple block module
For Coverage
AirDoctor 5500
The AirDoctor 5500 is a large air purifier designed for large homes or small offices.
The AirDoctor 5500 would be an excellent choice for purification performance and large coverage. With its 6 patented filter designs, it can handle large open areas
For Usability and Controls
Shark Neverchange
The Shark NeverChange is from the latest HP300 air purifier series from Shark.
It offers a wide range of user settings and air quality display information. This would be an excellent choice for users that want a power on and forget system.
For Purification
Oransi Mod+
The Oransi Mod+ is the successor to the Oransi Mod
This high performance air purification system is excellent for medium to large sized rooms that need superior purification.
FAQs
Use Also Asked to find relevant FAQs. And/or just create a few of your own that you think are relevant in case where Also Asked isn’t providing good questions.
Yes, Xiaomi Pro 4 has an ionizer. The Ionizer is automatically turned on when the system is activated.
Depending on the environment and amount of smoke, it can help filter the air and remove the smoke. The Xiaomi Pro 4 uses a carbon filter (in addition to other filters), which can help to remove VOCs and odors. However, this is specific to air quality, not fabrics and other surfaces that can retain the cigarette smell.
This specific model has a proprietary filter that is not HEPA.