At first, you might think that the Blueair 511i Max and 311i Max are completely identical air purifiers, and that is partially true.
However, the Blueair 311i Max is a much larger model and features a slightly different, wider design, which is reflected in its specifications.
The 511i Max has a CADR of 152 CFM (258 mÂł/h), while the 311i Max delivers a significantly higher CADR of 250 CFM (425 mÂł/h).
Both models work with Blueair’s smart app, come with a few smart features, and are extremely easy to use. However, there can only be one winner.
Our Verdict
The Blueair 511i Max and 311i Max are two truly remarkable air purifiers, and whichever one you choose, you will not make a wrong decision.
In practice, the choice between these two air purifiers should mainly depend on the size of the room where you plan to use the air purifier. For larger rooms, the 311i Max is the better option, while the 511i Max is more suitable for smaller spaces.
However, since I always pick a winner in my comparisons, this time it goes to the Blueair 311i Max. It offers a higher CADR, a larger filter, and slightly better noise optimization.
If you have any questions about these two Blueair air purifiers, feel free to leave a comment in the comments section below the article.
Specs: Blueair 511i Max Vs Blueair 511i Max
| Product Image |  |  |
| Manufacturer | Blueair | Blueair |
| Model | 511i Max | 311i Max |
| Dimensions (inches / cm) | 10.6 x 10.6 x 18.9 inches (26.9 x 26.9 x 48 cm) | 19 x 12.5 x 12.5 inches (48 x 32 x 32 cm) |
| Weight (pounds / kg) | 4.2 lb (1.9 kg) | 7.8 lb (3.56 kg) |
| Clean Air Delivery Rate (CADR) | 152 CFM (258 mÂł/h) | 250 CFM (425 mÂł/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. | 236 sq. ft. (22 m²) | 387 sq. ft. (36 m²) |
| Performance Ratings Performance Ratings Score Summary: 8.3 - Average Score (93 products) 9.9 - Best Score (1 products) 1 - Worst Score (1 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 | Washable Pre-filter, Particle Filter, Activated Carbon Filter, and HEPASilent | Washable Pre-filter, Particle Filter, Activated Carbon Filter, and HEPASilent |
| Filter Replacement Indicator | Yes | Yes |
| Filter Life | up to 9 months | 6-9 months |
| Power Consumption
Power Usage Summary: Our extensive testing of 93 air purifiers revealed the following power consumption insights:
Check out our power consumption calculator tool. | 20W | 30W |
| Operating Costs Ratings Operating Costs Ratings Score Summary: 8.9 - Average Score (93 products) 10 - Best Score (2 products) 1.7 - 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 - Sleep Mode, Speed 1, Speed 2, and Speed 3 | 4 - Sleep Mode, Speed 1, Speed 2, and Speed 3 |
| Air Quality Sensor Air Quality Sensor Summary: Out of 93 air purifiers tested, only 46 have the air quality sensor. | Yes | Yes |
| Air Quality Indicator | Yes | Yes |
| Auto Mode Auto Mode Summary: Out of 93 air purifiers tested, only 47 have auto mode functionality. | Yes | Yes |
| Smart App Smart App Summary: Out of 93 air purifiers tested, only 28 have smart app functionality. | Yes | Yes |
| Voice Control Voice Control Summary: Out of 93 air purifiers tested, only 27 have voice control functionality. | Yes | Yes |
| Other Features | Washable Pre-filter | Washable Pre |
| Noise Level (low – high) | 40.1 – 61.6 dBA | 40.2 – 59.5 dBA |
| Noise Ratings Noise Ratings Score Summary: 9.3 - Average Score (93 products) 10 - Best Score (1 products) 7.6 - 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 | Bedrooms Allergies Small Spaces Dust Low Energy Cost | Living Rooms Offices Low Energy Cost Large Spaces Dust Quiet Operation |
| Warranty | 3-year | 3-year |
| In-Depth Review | Blueair 511i Max | Blueair 311i Max |
| Price |
Performance Test – Comparison
We tested the performance of these two air purifiers in our predefined test rooms.
Testing procedure: Each device was placed in the room, the initial air quality was measured using a Temtop laser particle meter, and then the air purifier was run at maximum speed for 60 minutes. After that, we measured the final air quality.
Since the room coverage of these two Blueair models differs, we primarily tested them in different room sizes. However, we also performed a comparison test in the same 320 sq. ft. (30 m²) room for both units.
Particle Removal Tests - Comparison
We placed the Blueair 511i Max and Blueair 311i Max in two separate tests and measured their performance using the Temtop laser particle meter.
After 60 minutes, the Blueair 511i Max improved air quality by approximately 90%, while the Blueair 311i Max achieved an improvement of about 96%.
As expected, the Blueair 311i Max delivered better airborne particle removal performance. However, both models performed below average in our odor removal tests.
Noise Level Test – Comparison
These two Blueair air purifiers offer identical features, and the same applies to their fan speeds, as both models include four fan speeds along with an auto mode.
We measured their noise levels at each fan speed using a specialized noise measurement tool.
Noise Levels - Comparison
Comparison of noise levels at all fan speeds between the Blueair 511i Max and Blueair 311i Max air purifiers.
At the lowest speed, the Blueair 511i Max produces 40.1 dBA, while the Blueair 311i Max produces 40.2 dBA.
At maximum speed, the Blueair 511i Max reached 61.6 dBA, whereas the Blueair 311i Max was slightly quieter at 59.5 dBA.
One drawback of both air purifiers is that they produce an unusual noise at maximum speed, which is something I do not particularly like.
| Fan Speed | Blueair 311i Max (dBA) | Blueair 511i Max (dBA) |
|---|---|---|
| Sleep Mode | 40.2 dBA | 40.1 dBA |
| Speed 1 (Low) | 42.5 dBA | 41.3 dBA |
| Speed 2 (Medium) | 48.9 dBA | 44.1 dBA |
| Speed 3 (High) | 59.5 dBA | 61.6 dBA |
Based on our testing data, the Blueair 311i Max appears to be better optimized for noise, despite being a significantly larger air purifier with a more powerful motor.
Operating Costs – Comparison
Low power consumption and well-optimized motors characterize both Blueair air purifiers.
The Blueair 511i Max uses a 20W motor, while the Blueair 311i Max is equipped with a more powerful 30W motor.
Monthly Power Consumption Cost - Comparison
Comparison of monthly power consumption costs for the Blueair 511i Max and Blueair 311i Max air purifiers at all fan speeds.
If both air purifiers were run at maximum speed for 24 hours a day over one month, the estimated increase in electricity costs would be about $1.56 for the Blueair 511i Max and approximately $2.42 for the Blueair 311i Max.
| Fan Speed | Blueair 311i Max (W + $/month) | Blueair 511i Max (W + $/month) |
|---|---|---|
| Standby | 0.4W ($0.04) | 0.6W ($0.05) |
| Sleep Mode | 3.3W ($0.29) | 1.9W ($0.17) |
| Speed 1 (Low) | 4.8W ($0.42) | 2.5W ($0.22) |
| Speed 2 (Medium) | 12.7W ($1.11) | 4.7W ($0.41) |
| Speed 3 (High) | 27.6W ($2.42) | 17.8W ($1.56) |
In addition to electricity costs, there is also the cost of replacement filters, which need to be changed roughly every nine months for both models. Each air purifier also includes a washable pre-filter.
Considering that the replacement filter for the Blueair 311i Max is more expensive and that it uses a higher-power motor, I would say the Blueair 511i Max is better optimized and more affordable in terms of annual maintenance.
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