Big Circles in Minecraft - 21, 25 and 31 Diameter Plans Big circles are where guessing completely falls apart. A diameter 31 outline is 84 blocks placed in a precise pattern; nobody eyeballs that correctly. With a chart, though, a big circle is no harder than a small one - just more rows of the same counting. Block counts (outline / filled): Diameter 21: outline 56 blocks, filled 349 blocks. Diameter 25: outline 68 blocks, filled 489 blocks. Diameter 31: outline 84 blocks, filled 749 blocks. Use big circles for castle keeps, arena floors, spawn plazas and the base of mega towers. Build the outline at ground level first, live with it for a day, and only then commit to the walls - moving an 84-block outline is easy, moving a finished keep is not. Plan your own circle here: https://circlecraftlab.com/