What filter fits a Blueair 311i MAX air purifier?
The Blueair 311i MAX air purifier uses the AXPPF209 replacement filter.
Key takeaways
- Replacement filter part number: AXPPF209 (Blueair).
- True HEPA (H13) with an activated carbon layer.
- Replace about every 6 months.
- A cheaper aftermarket filter can fit the same slot - check reviews for real-world fit before buying.
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Frequently asked
What filter fits a Blueair 311i MAX air purifier?
The Blueair 311i MAX uses the AXPPF209 (AIRx Replacement Filter for Blueair 311i MAX Air Purifier).
Is the AXPPF209 True HEPA?
Yes - the AXPPF209 is a True HEPA filter, rated H13, meaning it's rated to capture at least 99.97% of 0.3-micron particles.
How often should I replace the AXPPF209?
About every 6 months under typical use, or sooner if airflow drops or your purifier's filter indicator lights up.
Should I buy the OEM filter or an aftermarket one?
The genuine Blueair AXPPF209 is the safe, exact-fit choice. A cheaper aftermarket filter can fit the same slot too - check reviews for real-world fit and filtration performance before buying, since air purifier filters generally aren't independently certified the way NSF-listed water filters are.