You could raise a lot of birds to use that space. I'd not hesitate to put 10 in it, even a dozen. Where the problem arises with smaller spaces is when integrating birds later to an existing flock. Birds raised together from chicks do quite well in small coops and medium sized runs.
I've had over fifteen grow outs voluntarily pack themselves into a 3x3x2 coop every night until twenty weeks of age. Now that's something I don't recommend but it gives you an idea of how well a batch of chicks raised together will behave.
I've had over fifteen grow outs voluntarily pack themselves into a 3x3x2 coop every night until twenty weeks of age. Now that's something I don't recommend but it gives you an idea of how well a batch of chicks raised together will behave.