Type the inside size of the cage and pick the species: the result says whether it meets the Merck Veterinary Manual minimum and bar spacing, and how it compares with European legal minimums.
Bird Cage Size Calculator - Minimum Size and Bar Spacing
Type the inside size of the cage and pick the species: the result says whether it meets the Merck Veterinary Manual minimum and bar spacing, and how it compares with European legal minimums.
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Bird cage size chart and checker in one
Pick the species, type the inside length, width and height of the cage, and the bird cage size calculator compares it with the minimum cage and bar spacing in the Merck Veterinary Manual. Add the bird's length and it also checks the cage against the minimums of Austria, Germany and Switzerland, three countries with cage sizes written into law or official guidelines, converted to inches.
Measuring the cage you have
- Species - thirteen birds in the four Merck groups. The group sets the minimum cage and the bar spacing.
- Bird length - optional, top of the head to the end of the tail, in inches. Needed for the European check on every species except budgies and cockatiels.
- Birds in the cage - adults only. The European rules add floor for each further pair or bird.
- Length, width and height - inside, in inches. Measure the height to the ceiling of the cage, not to the top of a stand. If you mix up length and width, the calculator swaps them.
- Bar spacing - optional, the gap between two bars, in inches. Fractions as decimals: 1/2 = 0.5, 5/8 = 0.625, 3/4 = 0.75.
Why a cage minimum is a floor, not a target
No US federal rule sets a minimum cage size for a pet bird kept at home, so owners lean on veterinary guidance. The most widely quoted is a short table in the Merck Veterinary Manual, which groups pet parrots into four sizes and gives each a minimum cage in inches and the widest safe bar spacing. It is a minimum for keeping a bird, not a description of a good cage, and it does not change with the number of birds.
Some European countries went further and wrote cage sizes into law. Austria's 2nd Animal Husbandry Ordinance sets a minimum for a pair by species or by body length, Switzerland's animal welfare ordinance (TSchV) sets floor area, volume and a minimum height, and Germany's federal ministry of agriculture (BMEL) publishes an expert opinion on keeping parrots with sizes by length. Next to the Merck table, these numbers show how differently the same bird can be housed depending on the standard.
Bar spacing is the other half of the check. A gap that is too wide lets a bird push its head through and get stuck; the usual advice is that when in doubt, the narrower spacing is the safer one. The Merck cell for the African gray group reads 0.751, which looks like a footnote mark or a range; the calculator takes the stricter 0.75 in.
Merck minimum cage and bar spacing by group
Dimensions are length by width by height, inside the cage. The floor and volume columns are worked out from them.
| Group | Minimum cage | In centimeters | Floor | Volume | Bar spacing |
|---|---|---|---|---|---|
| Budgerigar, cockatiel, lovebird, parrotlet | 20 x 20 x 30 in | 51 x 51 x 76 | 2.78 sq ft | 6.94 cu ft | 0.5 in |
| Conure, Poicephalus, caique, miniature macaw | 36 x 24 x 48 in | 91 x 61 x 122 | 6.00 sq ft | 24.00 cu ft | 0.75 in |
| African gray, Amazon, small cockatoo | 40 x 30 x 60 in | 102 x 76 x 152 | 8.33 sq ft | 41.67 cu ft | 0.75 in |
| Macaw, large cockatoo | 48 x 36 x 66 in | 122 x 91 x 168 | 12.00 sq ft | 66.00 cu ft | 1.5 in |
The same birds under European law
Minimums for a pair, converted from centimeters. Body length is from the top of the head to the end of the tail. The last column compares the floor with the Merck floor for the same bird.
| Bird | Rule | Minimum for a pair | Floor | Against Merck |
|---|---|---|---|---|
| Budgie | Austria | 31.5 x 15.7 x 23.6 in | 3.4 sq ft | close, longer but lower |
| Budgie | Switzerland | height from 15.7 in, up to 4 birds | 2.6 sq ft | below Merck, 4.2 cu ft |
| Cockatiel | Austria | 59.1 x 31.5 x 39.4 in | 12.9 sq ft | 4.6 times the Merck floor |
| Lovebird up to 5.9 in | Austria | 33.5 x 33.5 x 70.9 in | 7.8 sq ft | 2.8 times, and more than twice as tall |
| Short-tailed parrot 9.8 to 15.7 in (African gray, many Amazons) | Germany | 78.7 x 39.4 x 39.4 in | 21.5 sq ft | 2.6 times, but lower than Merck's 60 in |
| Short-tailed parrot 9.8 to 15.7 in | Austria | 118.1 x 78.7 x 78.7 in | 64.6 sq ft | 7.8 times, an aviary rather than a cage |
| Long-tailed parakeet, conure | Austria | 157.5 x 78.7 x 78.7 in | 86.1 sq ft | 14 times the Merck conure floor |
| Macaw over 23.6 in | Austria | 236.2 x 98.4 x 118.1 in | 161.5 sq ft | over 13 times the Merck macaw floor |
Patterns behind the two tables
Merck grows the cage upward, Europe grows it sideways. Merck's minimums are taller than they are long for every group, so a bird can climb. The Austrian and German minimums for the larger parrots are long and wide, because they are written for flight between perches.
The gap is smallest for budgies. A 20 x 20 x 30 in cage holds more floor than the Swiss budgie minimum (2.78 against 2.6 sq ft) and almost as much as the Austrian one (3.4 sq ft). From cockatiels upward the gap opens to several times the floor.
More birds, more floor, only in Europe. Austria and Germany add half the pair's floor for each further pair, Switzerland adds about 0.54 sq ft per bird past four budgies or six cockatiels. Merck gives one minimum per group.
Shape counts in Switzerland. For cages under about 21.5 sq ft, the minimum floor has to fit as a rectangle no longer than twice its width, so a very narrow cage can fail even with enough square feet.
Reading the verdict
The header turns red when the cage is shorter than the Merck minimum on any side or the bars are wider than the Merck spacing, and green otherwise. The European table below it shows each rule as meets it or too small, with the shortfall in inches, square feet or cubic feet. Two runs of the calculator:
A pair of budgies in a 30 x 18 x 24 in cage is red: 2 in too narrow and 6 in too low for Merck. It meets the Swiss minimum, misses the Austrian one by 1.5 in of length, and has 7.5 cu ft inside. An African gray in a 40 x 30 x 60 in cage with 1 in bars meets the Merck size but turns red on the bars, 0.25 in wider than the group's 0.75 in.
Cage size questions from bird owners
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