How to size an air purifier for a room with a vaulted or high ceiling: the volume-based CADR formula, plus worked examples for a bedroom and great room.

Size a garage or workshop air purifier by square footage, then match the filter to sawdust (HEPA) or paint and solvent fumes (HEPA plus carbon).

Size an air purifier for a home office under 150 sq ft, built for all-day use, paper dust, and printer and copier VOCs, plus a desk-placement diagram.

Match your kitchen air purifier to its square footage with this smoke-CADR sizing table, and learn why HEPA alone cannot remove cooking odors and VOCs.

One correctly sized air purifier covers most open floor plans up to 600 sq ft. See the CADR math, a sizing table, and when two units work better.

Size a basement air purifier correctly: tell moisture from airborne mold, use the 2/3 CADR rule plus a basement oversize tip, and skip ozone generators.

A 500 sq ft studio needs about a 325 minimum smoke CADR air purifier (AHAM two-thirds rule), sized to the whole open space, not just the bed area.

Size an air purifier for a nursery, place it safely near the crib, manage cords, and set nap-time noise limits, based on EPA, AHAM, CPSC and WHO guidance.

Use the two-thirds CADR rule to size your bedroom air purifier, then size up slightly so it runs quietly near WHO’s 30 dB nighttime noise guideline.

A room-by-room sizing table for air purifiers: CADR targets, air changes per hour, and the top factor for bedrooms, nurseries, basements and kitchens.