Air purifier sizing Last reviewed June 30, 2026
What Size Air Purifier for Smoke and Wildfire? CADR Guide
By the WhatSize editorial team 4 min read Standards-reviewed
For smoke removal, you need an air purifier with a smoke CADR at least 2/3 of your room's square footage. A 300 sq ft room needs CADR 200+. For wildfire smoke, run the unit 24/7 on high and seal the room. The Coway AP-1512HH (CADR 240) is the top-rated smoke fighter under $250.
Why Smoke Filtration Needs Higher CADR Than Standard
Smoke particles (especially wildfire smoke PM2.5) are smaller and more numerous than standard household dust. The AHAM AC-1 standard recommends a smoke CADR of at least 2/3 of the room's square footage, but for heavy smoke conditions a 1:1 ratio (CADR = sq ft) provides better protection.
Smoke removal also requires continuous operation — smoke particles remain airborne for hours and recirculate through HVAC systems. The EPA recommends running your air purifier on high 24/7 during smoke events, which means noise and energy consumption matter as much as CADR. Look for units with a smoke-specific or auto mode that ramps up when particulate levels spike.
Top picks for this size
These Amazon-available picks meet the calculated spec. For region-specific or licensed contractor-installed options, consult a local professional. See our Disclaimers.
Recommended Air Purifiers for Smoke by Room Size
- Small room (150-250 sq ft): Levoit Core 300 (CADR 140 smoke) — good for bedrooms, runs quietly on medium
- Medium room (250-400 sq ft): Coway AP-1512HH (CADR 240 smoke) — best overall, auto mode adjusts to smoke levels
- Large room (400-600 sq ft): Winix 5500-2 (CADR 380 smoke) — washable pre-filter captures larger smoke particles
- Open plan / whole floor (600-1,000 sq ft): Alen BreatheSmart 75i (CADR 347, intended for larger spaces) or two medium units at opposite ends
Frequently asked questions
What CADR do I need for wildfire smoke?
AHAM recommends smoke CADR at least 2/3 of your room's sq ft. For heavy smoke, aim for 1:1. A 300 sq ft room needs CADR 200-300 for smoke. Check the CADR for smoke specifically — it's different from dust and pollen CADR.
Does HEPA filter remove smoke smell?
True HEPA captures smoke particles (99.97% at 0.3 microns), but smoke smell also requires an activated carbon filter for volatile organic compounds (VOCs). Look for units with at least 1-2 lbs of carbon media for effective odor removal.
Should I run my air purifier on high during wildfire smoke?
Yes. Run it on high for the first hour to clear the air, then switch to medium or auto mode. Seal windows and doors, and run the purifier 24/7 until air quality improves. Replace the filter after smoke season.
You might also need
More air purifier sizing guides
- What Size Air Purifier for a Bedroom? CADR Guide
- What Size Air Purifier for a Large Room (500+ Sq Ft)?
- What Size Air Purifier for a Living Room?
- What Size Air Purifier Do Pet Owners Need?
- What Size Air Purifier Do You Need for Allergies?
- How Many Air Changes per Hour Do I Need? (ACH Chart)
- What Is CADR? Air Purifier Sizing Explained
- What Size Air Purifier for an Office or Home Office?
- What Size Air Purifier for a Basement?
Still choosing between sizes? Compare: CADR vs ACH