Sizing · reference
Air Purifier for a 100 Sq Ft Room: 65 CADR
EPA publishes a minimum clean air delivery rate of 65 cfm for a 100 square foot room, assuming an eight-foot ceiling.
Updated 30 Aug 2026
ReadSizing & CADR
The published minimum CADR for each room size, and the sizing mistakes that follow from ignoring it.
26 pages6 from the EPA table
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16 pagesSizing · reference
Air Purifier for a 200 Sq Ft Room: 130 CADR
EPA publishes a minimum clean air delivery rate of 130 cfm for a 200 square foot room, assuming an eight-foot ceiling.
Updated 30 Aug 2026
ReadSizing · reference
Air Purifier for a 300 Sq Ft Room: 195 CADR
EPA publishes a minimum clean air delivery rate of 195 cfm for a 300 square foot room, assuming an eight-foot ceiling.
Updated 30 Aug 2026
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Air Purifier for a 400 Sq Ft Room: 260 CADR
EPA publishes a minimum clean air delivery rate of 260 cfm for a 400 square foot room, assuming an eight-foot ceiling.
Updated 30 Aug 2026
ReadSizing · reference
Air Purifier for a 500 Sq Ft Room: 325 CADR
EPA publishes a minimum clean air delivery rate of 325 cfm for a 500 square foot room, assuming an eight-foot ceiling.
Updated 30 Aug 2026
ReadSizing · reference
Air Purifier for a 600 Sq Ft Room: 390 CADR
EPA publishes a minimum clean air delivery rate of 390 cfm for a 600 square foot room, assuming an eight-foot ceiling.
Updated 30 Aug 2026
ReadSizing · reference
Why "Covers 1,500 sq ft" Means Very Little
Coverage claims are not standardised. The published minimum CADR is. See why the room-size row beats the box headline every time you compare.
Updated 30 Aug 2026
ReadSizing · reference
High Ceilings Change the Purifier You Need
Every published CADR assumes an eight-foot ceiling, so a taller room makes the table under-read.
Updated 30 Aug 2026
ReadSizing · reference
Two Small Air Purifiers or One Large One?
The minimums are published per room, so the floor plan decides this rather than total area.
Updated 30 Aug 2026
ReadSizing · reference
Five Air Purifier Sizing Mistakes
The five ways people end up with a unit that cannot do the job, and the published CADR row that would have prevented each mistake.
Updated 30 Aug 2026
ReadSizing · reference
Whole-House or Room Air Purifier?
One published minimum per room is why a single hallway unit does not cover a home.
Updated 30 Aug 2026
ReadSizing · reference
What CADR Do I Need? Start With the Room
The whole method in one page: measure the room, read the published minimum, check the smoke rating.
Updated 30 Aug 2026
ReadSizing · reference
Where to Put an Air Purifier in a Room
Clearance matters more than which corner you choose, because every published CADR assumes the air can actually reach the machine.
Updated 30 Aug 2026
ReadSizing · reference
Should You Run an Air Purifier All the Time?
Particles return the moment it stops, so the cost side is filter life and electricity.
Updated 30 Aug 2026
ReadSizing · reference
Why an Oversized Air Purifier Is Quieter
A larger unit reaches the same CADR at a lower fan speed, the one good case for going above the minimum.
Updated 30 Aug 2026
ReadSizing · reference
Do Air Purifiers Actually Work?
They do one measurable thing well, and several advertised things without any published rating.
Updated 30 Aug 2026
ReadExplainers
10 pagesSizing · explainer
Air Purifier Not helping allergies: Likely Causes
A common complaint, and the handful of causes worth checking before replacing the unit.
Updated 30 Aug 2026
ReadSizing · explainer
Air Purifier Smells bad: Likely Causes
A common complaint, and the handful of causes worth checking before replacing the unit.
Updated 30 Aug 2026
ReadSizing · explainer
Air Purifier Too loud: Likely Causes
A common complaint, and the handful of causes worth checking before replacing the unit.
Updated 30 Aug 2026
ReadSizing · explainer
Air Purifier Blowing dusty air: Likely Causes
A common complaint, and the handful of causes worth checking before replacing the unit.
Updated 30 Aug 2026
ReadSizing · explainer
Air Purifier Filter light will not reset: Likely Causes
A common complaint, and the handful of causes worth checking before replacing the unit.
Updated 30 Aug 2026
ReadSizing · explainer
Air Purifier Stopped working: Likely Causes
A common complaint, and the handful of causes worth checking before replacing the unit.
Updated 30 Aug 2026
ReadSizing · explainer
Air Purifier Making a rattling noise: Likely Causes
A common complaint, and the handful of causes worth checking before replacing the unit.
Updated 30 Aug 2026
ReadSizing · explainer
Air Purifier Blowing cold air: Likely Causes
A common complaint, and the handful of causes worth checking before replacing the unit.
Updated 30 Aug 2026
ReadSizing · explainer
Air Purifier Using more power: Likely Causes
A common complaint, and the handful of causes worth checking before replacing the unit.
Updated 30 Aug 2026
ReadSizing · explainer
Air Purifier Never reaches clean: Likely Causes
A common complaint, and the handful of causes worth checking before replacing the unit.
Updated 30 Aug 2026
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