Nether Portal Sizing The portal must be rectangular (e.g. 3x3, 4x2, 3x5, but no circles). It has a maximum internal size of 21x21. It must be at least 3 tall, and at least 2 wide (not including the frame, with the frame that ends up as 5x4). If you build multiple portals in front of each other and light them, only the rear most portal will be visible, but all will function. This may be a bug. Found at http://gaming.stackexchange.com/questions/137611/what-shapes-can-nether-portals-be Important Information is you have to light it with a diaspenser and flint and steel inside it with a lever/button Here is a video guide of actually making it You can make it much smaller I will post screenies of mine in a little.