The canvas size in the ArtRage mobile editions is capped for memory reasons. These apps run on a wide range of devices, and many have very limited memory and processing power available. Canvas size is on of the most memory intensive features, so the app implements a maximum size.
Maximum Canvas Sizes in the Mobile ArtRage Apps
If you need a larger painting
|ArtRage for iPhone||ArtRage for iPad on iPad 1 devices||ArtRage for iPad on iPad 2 and later, iPad Pro 9″||ArtRage for iPad on iPad Pro 11″||ArtRage Touch||ArtRage for Android|
|960 x 640||1400 x 1400||2048 x 2048||4096 x 4096||2048 x 2048||2048 x 2048|
, it is possible, in some cases, to resize your work. See How to Increase the Size of Your ArtRage Mobile Paintings
and How to choose a Canvas Size in ArtRage