How many birds will fit in your cage?As a general rule, 3-4 square feet of floor space is required per pair of finches. If you know the dimensions (in inches) of the cage you are considering placing birds into, you can use the calculator below to find out how many birds your cage may comfortably house. (Remember that 12 inches are in one foot, and approximately 3.3 feet are in one meter.) Keep in mind that there are species and individual differences, and that some birds may require even more than this amount of space to maintain a peaceful environment.
Please note that the height of a cage should be proportional to its width and length, but is not an important factor when determining how many birds a cage can adequately hold. The main reason for this is due to the behavior of finches: birds tend to feel more secure when they are perched high in their enclosure. Because of this, the finches will often congregate in the upper aspect of the enclosure (especially to roost) and will often fight over the upper perches/territories if their enclosure does not have enough width or depth to give each pair their own "personal space."
3-4 square feet of space per pair may seem like a lot of room for two tiny birds, but the small size of the birds does not take away from their need to have a sufficiently sized territory. If you try to cram more birds into your enclosure than it can comfortably hold, the birds will feel overcrowded and will become stressed. Stressed birds often suffer from health problems and will often mutilate themselves and/or take their stress out on cage mates (which leads to hissing, chasing, plucking, injuries, and so forth). In some circumstances, finches have been known to kill each other while fighting over territory or resources. Some species are more likely to get along than others, but even the most "laid back" species may defend their favorite perch, hissing at and chasing other birds which encroach on their personal space. The minimum of 3-4 square feet of space per pair is a general recommendation which has been found to prevent these potential problems for the commonly kept finch species in most cases.