>>4072248If you don't need to print your works and want to make it simple, my rule is: The shortest side has to be minimum 2160p so it looks good on vertical and horizontal 1080p, 1440p and 2160p screens.
Examples:
Square: 2160x2160
Widecreen: 3840x2160 (recommended for wallpapers and Twitter)
Panoramic: 5076x2160
Instagram portrait: 2160x2700 (locked AR)
Portrait: 2160x3000
18:9 Phone Wallpaper: 2160x4320 (meh, most phones don't reach that resolution, just make suke your protraits look good when they're cropped to that aspect ratio)
Duplicate or triplicate those sizes if you feel they're not enough for you, but don't go lower than that.