Any amount can be added (within reason), but we recommend:Up to 10 animals on the smallest 5x7"Up to 14 animals on the mediums 8x10" or A4 (8.3 x 11.7")Up to 18 animals on the large A3 (11.7 x 16.5")This is just so that they don't look too tiny on the page when they're scaled down to fit on. If you would like a particularly large amount of animals (20 plus), please send us a message with your request so we can confirm whether it's possible.