How to build perfect circles and domes in Minecraft

Pick a width, draw the shape in our Circle & Sphere Generator and copy it row by row. A hollow circle 15 blocks wide takes 40 blocks; the dome on top of it takes 285 more, over 8 layers. The method is the same in Java and Bedrock Edition.

The width is twice the radius. With an odd width, one block sits in the exact center: handy for a beacon, a fountain or a pillar. With an even width, the center falls between four blocks. These counts come from the generator:

In the generator, a radius of 7.5 gives a width of 15 and a radius of 8 a width of 16.

Stand where the center goes and press F3 to note your X and Z. For a 15-wide circle, the outermost blocks sit 7 blocks from the center block, along each of the four directions. Place a marker block at each of these 4 points. For an even width, the center is a square of 2 by 2 blocks, and you count from its edges.

A circle is the same shape in all four quarters, so read one quarter of the grid and repeat it. Each quarter is even mirrored in its middle. For a 15-wide hollow circle, the outline reads 5, 2, 1, 2, 5:

1. a flat run of 5 blocks centered on each marker;
2. one block in and one block over, a run of 2;
3. then a single block on the diagonal;
4. then a run of 2 turning the other way, which meets the flat run of 5 of the next side.

Bigger circles have longer flat runs and more steps, but the rule is the same: runs get shorter towards the diagonal, then longer again. The generator grid shows every run, with the center lines in blue.

A round tower is the same ring repeated. Multiply: a hollow 15-wide ring of 40 blocks, 10 layers high, takes 400 blocks. For thicker walls, raise Wall thickness in the generator: 2 blocks thick, the same ring takes 76 blocks per layer. Leave gaps for the door and the windows as you go up.

Pick Dome and Hollow in the generator. Layer 1 is the widest one, the base of the dome, and each next layer is smaller. The faded cells show the layer below, so you can line each ring up with the one you just placed.

• A dome has about half as many layers as its width: 8 layers for 15 blocks wide.
• The top layers step in fast: build them from Scaffolding. 6 Bamboo and 1 String make 6 Scaffolding; jump to climb, sneak to go down.
• Hollow keeps only the outer shell, without holes. Glass makes a greenhouse, and the same dome on a ring of walls makes a tower roof.
• Use Print all layers under the grid to keep every layer on paper or as a PDF.

Circles and domes in blocks always have steps. On large builds, place stairs or slabs in the corners of the steps to soften the curve. Pick blocks that come with stairs and slabs, such as Stone Bricks, so that the whole outline uses one material. For whole houses built layer by layer, see the Blueprints.