Minecraft circle and oval generator

1. Pick a size. Odd sizes (like 21) have a single centre block, which is easier to line up from.
2. Place a marker block at the centre, then build out the two dashed centre lines first.
3. Work row by row from the top, counting blocks with the list under the picture.
4. Building a tower or dome? Use the thick outline so the walls have no gaps when seen from the side.

Thin outlines connect at the corners only, which looks cleanest from above. Thick outlines add a block wherever two touch diagonally, so mobs and water can't slip through. Filled gives you a solid disc for floors, ponds and roofs.

Building a dome or a planet? The sphere generator gives you every layer. Linking a base to the Nether? The nether portal calculator converts your coordinates so the portals line up.