Minecraft Circle Generator

Each cell represents the center of one Minecraft block. The generator places the mathematical center at (diameter − 1) ÷ 2 on both axes and gives the outside of the circle a radius of diameter ÷ 2. A cell is selected when the distance from its center to the circle center is no greater than that outside radius.

Filled mode keeps every selected cell. Outline mode also calculates an inner radius equal to the outside radius minus the chosen thickness, then removes cells that fall completely inside that boundary. The result is a discrete pixel circle rather than a smooth vector curve, which is exactly the geometry a block build needs.

• Odd diameters have one center row, one center column, and a single center block.
• Even diameters center the shape between four blocks, so the middle spans two rows and two columns.
• Every row is generated from the same distance test, keeping opposite sides symmetrical.

Set Diameter to 21, choose Outline, and leave Thickness at 1. The center is block coordinate 10 on the zero-based grid, the outer radius is 10.5, and the inner radius is 9.5. A block is kept only when its center distance is at most 10.5 and greater than 9.5.

The top and bottom rows contain seven blocks each, the next mirrored pair contains four each, and the remaining 17 rows contain two edge blocks each: (7 × 2) + (4 × 2) + (17 × 2) = 56 outline blocks. The result has the same eight-way symmetry builders expect from a midpoint-style pixel circle, while this implementation gets each cell from the stated distance-annulus test.

• The displayed 56-block count is the exact number of highlighted cells.
• A 2-block outline uses the same outside edge but keeps an additional inner band.
• Switching to Filled changes the material total because the interior cells are retained.

Treat the generated grid as a top-down layer. For a tower, it is the footprint you repeat vertically; for a dome, it is usually the widest base layer, not the complete dome. Start at a cardinal point or on the center row, finish one quadrant, and mirror it. That workflow makes an accidental run of three blocks where the pattern needs two much easier to spot.

• Bring the exact block total plus a small construction buffer.
• Use contrasting temporary blocks for the center axes and remove them after the outline closes.
• For very large circles, follow the row-run list rather than judging curvature from ground level.

There is no single uniquely correct pixel circle for every diameter. This generator uses block-center distance, producing consistent symmetry and a defensible geometric boundary; another guide may use a different rasterization rule and place a few edge blocks differently. The preview is exact for this algorithm, but decorative depth, terrain clearing, doors, buttresses, and vertical shaping are outside its material count.

• Diameters are rounded to whole blocks because partial Minecraft blocks cannot be placed.
• The maximum 101-block diameter keeps the interactive grid readable and responsive.
• Outline thickness is constrained by the radius so the inner boundary cannot invert.