Air Purifier Sizing for a Bird Room: CADR by the AHAM Rule and by Air Changes
Two ways to size an air cleaner for a bird room, AHAM's two-thirds rule and the air-changes formula, with examples and the limits of CADR.
Pet bird cage buying guides
Which cage is big enough for a cockatiel, a conure or a macaw, what bar spacing keeps a parakeet in and its head out, and which perches, stands and lights the avian vets recommend. Every guide shows its sources and the sizing behind the pick.

Seven budgie cages measured against the Merck 20 x 20 x 30 and VCA 12 x 12 x 24 minimums and the 0.5-inch bar spacing, with who should skip each.

The Merck and VCA minimums for every common pet bird in one table, the wingspan rules behind them, and how to measure a cage against them.

Six cockatiel cages against the Merck and VCA minimums, with the honest note that most 5/8-inch cages are wider-barred than Merck's figure.

Seven flight cages compared on flight length, bar spacing, gauge and price, from a $43 stackable box to an 80-inch parrot flight.
Specs from the source
Figures come from maker spec sheets and manuals, linked on the page.
A clear pick
Each guide names what we would buy, for whom, and what to skip.
Sources listed
Every guide ends with the documents it was built from.
New and updated buying guides, comparisons and how-tos.
Two ways to size an air cleaner for a bird room, AHAM's two-thirds rule and the air-changes formula, with examples and the limits of CADR.
Twelve states ban Quaker parrots as pets, three require a permit and three attach conditions. Check your state, with the regulation linked.
Three AHAM-rated HEPA purifiers sized to a bird room by CADR, the 2/3 rule applied to each, and the big-number units left out for publishing no CADR.
Nine cleaning products judged on label directions, liners by size and count, baths and covers, plus the wash-rinse-disinfect-dry sequence from the sources.
Seven grey and Amazon cages against the Merck 40 x 30 x 60 and VCA 36 x 36 x 48 minimums at 3/4 to 1-inch spacing, with where each falls short.
Six conure cages against the Merck 36 x 24 x 48 and VCA 36 x 36 x 36 minimums, with the honest finding that most retail conure cages fall short.