Minecraft Round Nether & End Portal Frame Generator

The Round Nether & End Portal Frame Generator is a specialized architectural layout guide for builders who want to break free from Minecraft's default 4×5 rectangular Nether portal frames. While the purple portal blocks themselves must fill a contiguous rectangular or custom shape within a valid frame, embedding that portal inside a massive, 2D or 3D circular obsidian ring turns a basic utility doorway into a jaw-dropping dimensional rift.

This tool calculates the exact obsidian frame layouts for round portals up to the maximum 23×23 vanilla portal limit, while providing circular sanctuary layouts for surrounding the End Portal in stronghold chambers.

Creating custom circular portals in survival requires obeying vanilla portal mechanics:

• The 23×23 Vanilla Limit: In unmodded Minecraft, the interior airspace of a Nether portal can be at most 21×21 blocks, meaning the outer obsidian frame cannot exceed 23×23 blocks. To build the largest possible functional circular portal in vanilla, generate an outline circle of Diameter 23!
• Hiding the Rectangular Inner Frame: Because a portal only lights if the immediate frame enclosing the air is a complete rectangle, builders achieve round portals by constructing a 21×21 rectangular obsidian sheet, lighting the portal, and then encasing the front and back corners in a curved circular frame of stone, blackstone, or obsidian!
• Mega-Portals (Modded or Illusion): For diameters larger than 23 blocks (e.g., Diameter 51), builders create multi-portal illusions by stacking multiple 23×23 portal frames side by side behind a giant circular gateway opening!

Follow these steps to construct an ancient, magical circular portal gateway:

• Step 1: Build the Obsidian Skeleton: Construct a standard rectangular obsidian portal frame (for example, 15 blocks wide by 15 blocks high) and ignite it with flint and steel.
• Step 2: Generate Your Circle Overlay: Set our tool to Diameter 15 in Outline Mode using Polished Blackstone or Cryo-Obsidian.
• Step 3: Layer the Front and Back: Build the circular ring directly 1 block in front of and 1 block behind the purple portal blocks, concealing the sharp rectangular obsidian corners behind smooth circular stonework.
• Step 4: Add Dimensional Spilling: Decorate the ground around the bottom of your circle with Netherrack, Crimson Nylon, and Magma blocks to make it look like the Nether is spilling out into the Overworld!

Circular End Portal Hubs: While you cannot move the 3×3 End Portal frame in vanilla survival, you can transform the dingy Stronghold room into a grand sanctuary! Use our generator to dig a Diameter 25 circular chamber centered exactly on the End Portal, replace the walls with End Stone Bricks and Purpur pillars, and build a glass dome floor over a void pit!

Sword-in-the-Stone Portal Rings: Use our Angled & Tilted Circle math to build a giant 45-degree tilted obsidian ring that slices diagonally into the ground like a fallen celestial ring, with a glowing Nether portal burning inside the upper loop!