With so many air purifier brands out there, it’s not easy to rise to the top and be the best. In this article, I will compare two air purifiers from premium brands, which are top of the class: the Alen BreatheSmart FLEX and the Levoit Core 400S.
The first thing I notice about these two air purifiers is the difference in room coverage (CADR) and in number of features. The Alen covers rooms of up to 300 sq. ft. (28 m²), while the Levoit covers rooms of up to 403 sq. ft. (37 m²).
They both use three-stage filtration technology consisting of a pre-filter, a main filter, and an activated carbon filter. These are undoubtedly high-efficiency filters, and the reason these air purifiers achieved outstanding results in performance tests.
Additionally, I like the Alen pellet-based carbon filter, which consists of 2+ lbs of carbon pellets.
Other things worth mentioning are the air quality sensor, air quality indicator, auto mode, smart app, and many more advanced features available only on the Levoit Core 400S. On the other hand, the Alen FLEX is minimalism-oriented, so it doesn’t have many advanced features. It has basic features such as a timer, display off, and filter reset indicator.
Our Verdict
Frankly, the Alen FLEX and the Levoit Core 400S are two outstanding air purifiers that provide excellent results in all tests performed.
However, after comparing all the specifications, characteristics, and test results, I declared the Levoit Core 400S the winner in this battle. It has a larger CADR, is cheaper to maintain, has slightly longer-lasting filters, and boasts plenty of advanced features, including an air quality sensor. It was also faster in the smoke removal test.
Even though I picked the Core 400S as the winner, it doesn’t mean the Alen FLEX isn’t a good buying option. It’s actually a great option, which I would suggest over the Core 400S if you are looking for a slightly quieter air purifier that excels at neutralizing bad odors and removing smoke.
Please use the comment box below the article if you have questions about these two air purifiers.
Specs: Alen FLEX Vs Levoit Core 400S
| Product Image |  |  |
| Manufacturer | Alen | Levoit |
| Model | BreatheSmart FLEX | Core 400S |
| Dimensions (inches / cm) | 8.5 x 15 x 25 inches (21,6 x 38,1 x 63,5 cm) | 10.8 x 10.8 x 20.5 inches (27.4 x 27.4 x 52 cm) |
| Weight (pounds / kg) | 15 lb (6.8 kg) | 10.5 Ib (4.8 kg) |
| Clean Air Delivery Rate (CADR) | 187 CFM (317 m³/h) | 260 CFM (442 m³/h) |
| Coverage (4.8 ACH)
Room Coverage Explanation: ACH is a measurement used in indoor air quality management to indicate how many times the air within a defined space is changed/moved through the filter media.
For more details, visit our ACH calculator tool. | 300 sq. ft. (28 m²) | 403 sq. ft. (37 m²) |
| Performance Ratings Performance Ratings Score Summary: 8.5 - Average Score (67 products) 9.8 - Best Score (2 products) 2.5 - Worst Score (2 products) We use the Temtop LKC-1000S laser particle meter to test the particle removal efficiency of every air purifier. It measures PM2.5 (µg/m3), PM10 (µg/m3), Particles (per/L), and HCHO (mg/m3) in the air, and also calculates the AQI. You can read more about our testing methodology here. | ||
| Filtration Technology | Pre-filter, True HEPA Filter, and Activated Carbon Filter | Pre-filter, True HEPA Filter, and Activated Carbon Filter |
| Filter Replacement Indicator | Yes | Yes |
| Filter Life | 9-12 months | up to 12 months |
| Power Consumption
Power Usage Summary: Our extensive testing of 67 air purifiers revealed the following power consumption insights:
Check out our power consumption calculator tool. | 50W | 38W (24W European Model) |
| Operating Costs Ratings Operating Costs Ratings Score Summary: 9.1 - Average Score (67 products) 10 - Best Score (2 products) 8 - Worst Score (1 products) We measure the power usage at all speeds using an energy meter, after which we calculate how much it would cost to use the device at a particular fan speed for one month. For reference, we use an energy price of $0.12 per kWh. You can read more about our testing methodology here. | ||
| Number of Fan Speeds | 4 – Speed 1, Speed 2, Speed 3, and Turbo Mode | 5 – Sleep Mode, Low Mode, Medium Mode, High Mode, and Turbo Mode |
| Air Quality Sensor Air Quality Sensor Summary: Out of 67 air purifiers tested, only 31 have the air quality sensor. | No | Yes |
| Air Quality Indicator | No | Yes |
| Auto Mode Auto Mode Summary: Out of 67 air purifiers tested, only 32 have auto mode functionality. | No | Yes |
| Smart App Smart App Summary: Out of 67 air purifiers tested, only 20 have smart app functionality. | No | Yes |
| Voice Control Voice Control Summary: Out of 67 air purifiers tested, only 20 have voice control functionality. | No | Yes |
| Other Features | Control Panel LockTimer | Display OffDisplay LockTimer |
| Noise Level (low – high) | 41.2 – 53.7 dBA | 42.1 – 59.9 dBA |
| Noise Ratings Noise Ratings Score Summary: 9.3 - Average Score (67 products) 10 - Best Score (1 products) 8.2 - Worst Score (1 products) We use a special noise measurement tool to test the noise level of the air purifier at all speeds. We measured the noise level on the dBA scale. You can read more about our testing methodology here. | ||
| Best Suited For | Living Rooms Bedrooms Kitchens Allergies Neutralizing VOCs Dust Mold Quiet Operation | Living Rooms Kitchens Allergies Large Spaces Dust Smart Home Integration Air Quality Monitoring |
| Warranty | 1-year to Lifetime | 2-year |
| In-Depth Review | Alen BreatheSmart FLEX | Levoit Core 400S |
| Price | Check Price on Amazon | Check Price on Amazon |
Performance Test – Comparison
When it comes to performance testing, specifically the efficiency of these air purifiers in removing particles, the first thing I want to address is CADR. The Alen FLEX has a CADR of 187 CFM (317 m³/h), while the Levoit is a much stronger air purifier with a CADR of 260 CFM (442 m³/h).
Given their capacities, I tested both devices in a room size of 560 sq. ft. (52 m²). What’s interesting about this test is that the Alen FLEX improved air quality by 3 percent more than the Levoit.
Particle Removal Tests - Comparison
We placed the Alen FLEX and Levoit Core 400S in two separate tests and measured their performance using the Temtop laser particle meter.
The Levoit Core 400S reduced the concentration of PM2.5 particles from 108.2 to 10.1 µg/m³, which is an impressive 91% improvement in air quality. On the other hand, the Alen FLEX reduced the amount of PM2.5 particles from 96.3 to 5.7 µg/m³, resulting in an air quality improvement of about 94%.
Overall, the Alen showed slightly better results in this test, even though the room in which it was tested is much larger than the recommended size.
Smoke Box Test – Comparison
The Alen FLEX and Levoit Core 400S are two fantastic air purifiers, and each test we did on these two has been more interesting than the last.
This was especially true in the smoke removal test.
When comparing filtration technology, the Alen FLEX has a far superior carbon filter compared to the Levoit. However, the filter in the Alen is much denser, which reduces airflow and affects the speed in the smoke test.
The Alen FLEX removed all the smoke from the smoke box in just 32 seconds, while the Levoit Core 400S took an impressive 15 seconds to clear the box.
Honestly, I didn’t expect such a significantly better result from the Levoit, but I can assure you that both devices are very effective at neutralizing bad odors.
Noise Level Test – Comparison
What stands out about these two devices is that they have multiple fan speeds. The Levoit Core 400S has five speeds, while the Alen FLEX has four. The biggest difference is that the Levoit Core 400S has a sleep mode as well as an auto mode.
Noise Levels - Comparison
Comparison of noise levels at all fan speeds between the Alen FLEX and Levoit Core 400S air purifiers.
However, despite not having a sleep mode, the Alen FLEX is much quieter at its lowest speed, producing a sound level of only 41.2 dBA, compared to 42.1 dBA for the Levoit.
Additionally, the Alen FLEX is one of the quietest and best-optimized air purifiers we have tested.
At maximum speed, the Alen FLEX is also quieter, with a sound level of 53.7 dBA, while the Levoit Core 400S produces 59.9 dBA.
| Fan Speed | Alen FLEX (dBA) | Levoit Core 400S (dBA) |
|---|---|---|
| Sleep Mode | - | 42.1 dBA |
| Speed 1 (Low) | 41.2 dBA | 43.6 dBA |
| Speed 2 (Medium) | 43.5 dBA | 47.8 dBA |
| Speed 3 (High) | 48.9 dBA | 55.4 dBA |
| Speed 4 (Turbo) | 53.7 dBA | 59.9 dBA |
To be clear, although the Alen is one of the quietest air purifiers we have tested, the Levoit Core 400S also falls into the quiet category. However, compared to the Alen, it is noticeably louder and struggles to compete in this test.
Operating Costs – Comparison
When comparing energy consumption, I have to say that Alen is also surprising in this regard. Although it uses a 50W motor, while Levoit uses 38W, it is generally a much smaller consumer and has a much better-optimized motor than Levoit.
If you were to leave these two devices running 24 hours a day at maximum speed for a month, your electricity bill would increase by about $2.13 for the Alen FLEX and approximately $3.06 for the Levoit Core 400S.
Monthly Power Consumption Cost - Comparison
Comparison of monthly power consumption costs for the Alen FLEX and Levoit Core 400S air purifiers at all fan speeds.
Not only at maximum speed, but the Alen FLEX is also a much smaller consumer at all other speeds.
In addition to energy consumption, there is also the cost of replacement filters, which last an average of up to 12 months for both devices but are much more expensive for the Alen FLEX.
| Fan Speed | Alen FLEX (W + $/month) | Levoit Core 400S (W + $/month) |
|---|---|---|
| Standby | 0.4W ($0.04) | 0.9W ($0.07) |
| Sleep Mode | - | 3.3W ($0.28) |
| Speed 1 (Low) | 2.7W ($0.24) | 5.8W ($0.5) |
| Speed 2 (Medium) | 6W ($0.53) | 8.8W ($0.77) |
| Speed 3 (High) | 14.2W ($1.24) | 16.1W ($1.41) |
| Speed 4 (Turbo) | 24.3W ($2.13) | 35W ($3.06) |
All in all, low energy consumption and affordable, long-lasting filters make these two devices very economical to maintain. I would say that the Levoit Core 400S is somewhat more affordable to maintain due to the much more affordable price of replacement filters compared to the Alen.
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