Common questions about air purifiers, CADR ratings, and filter replacements
CADR (Clean Air Delivery Rate) measures how much clean air a purifier delivers per minute in cubic feet (CFM). Higher CADR = faster air cleaning. For best results, choose a purifier with CADR ≥ 2/3 of your room's square footage. Use our CADR Calculator to find the right size.
HEPA 13: Medical-grade, captures 99.95% of particles ≥0.3μm. Best for severe allergies, asthma, wildfire smoke.
True HEPA: Captures 99.97% of particles ≥0.3μm. Industry standard, excellent for allergies and dust.
Basic HEPA: HEPA-type or HEPA-like, typically 90-95% efficient. Budget option for basic air cleaning.
Most HEPA filters last 6-12 months. Activated carbon filters (for odors) saturate faster, typically 3-6 months. Pre-filters should be washed monthly or replaced every 3 months. Check your model's manual or use our replacement filter guide to find compatible filters and replacement schedules.
OEM (Genuine): Guaranteed fit and performance, often more expensive. Best for warranty compliance.
Compatible (Aftermarket): Usually 30-50% cheaper, quality varies. Check reviews carefully. Our filter comparison shows both options with user ratings.
Yes, if you need odor removal! HEPA filters capture particles (dust, pollen, dander) but NOT gases or odors. Activated carbon is essential for: smoke (cigarette, cooking, wildfire), pet odors, chemical fumes (VOCs), and cooking smells. Look for "HEPA + Carbon" filters on our comparison page.
Energy costs vary by wattage. A 45W purifier costs ~$51/year running 24/7 (at $0.13/kWh). An 8W purifier costs only ~$9/year. Use our Energy Cost Calculator to calculate exact costs for your electricity rate.
ACH 2: Normal air quality
ACH 4: Good for allergies and dust
ACH 5: Recommended for pets or smoke
ACH 6+: Best for wildfire smoke or severe allergies
Use our calculator to determine required CADR based on your room size and desired ACH.
1. Measure room length × width to get square footage
2. Multiply by ceiling height to get room volume
3. Decide desired ACH (4 for allergies, 5 for pets/smoke)
4. Calculate: Required CFM = (Room Volume × ACH) ÷ 60
5. Find purifier with CADR ≥ required CFM
Or use our automatic calculator with room presets.
Yes, especially for allergies, asthma, or poor air quality. However, factor in total cost: a $50 purifier might cost $530 over 3 years (filters + energy), while a $200 efficient model might cost only $350. Use our Total Cost Calculator to see 3-year ownership costs.
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