Air Purifier Room Size Calculator for Allergies
Enter your room dimensions to find the minimum CADR you need — based on AHAM's 4.8 air changes per hour standard.
If you suffer from allergies, your air purifier isn't a nice-to-have — it's medical equipment. The right CADR rating determines whether you wake up congested or breathing freely.
For allergy sufferers, we recommend 5–6 ACH instead of the standard 4.8. Research published in the Journal of Allergy and Clinical Immunology shows that higher air turnover rates significantly reduce airborne allergen concentrations, leading to measurable symptom improvement.
A True HEPA (H13) filter is non-negotiable — it captures 99.97% of particles at 0.3 microns, including pollen (10–100 μm), dust mite allergens (1–40 μm), pet dander (0.5–100 μm), and mold spores (2–100 μm).
For a typical 12×12 ft bedroom (144 sq ft), aim for at least 116 CFM at 5 ACH. The calculator below will show you both the standard and allergy-optimized CADR targets.
Air Changes Per Hour (ACH) Reference
| Purifier CADR | ACH for Your Room | Rating |
|---|
💡 Tips for Allergies Air Purifiers
- ✓ For allergies, target 5–6 ACH instead of the standard 4.8 — the difference in symptom relief is significant.
- ✓ True HEPA (H13 or H14) is essential. Avoid "HEPA-type" or "HEPA-like" filters — they don't meet the same standard.
- ✓ Keep the purifier running 24/7 on low, not just when symptoms flare. Consistent filtration prevents allergen buildup.
- ✓ Pair with allergen-proof bedding covers for maximum dust mite control in bedrooms.
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