How to use the circle generator
Choose Circle or Ellipse, then set the size with the slider, the plus and minus buttons, or by typing a number. Pick a thickness: filled, a thin outline, a thick outline, or a custom wall width.
Drag the plan to move around, pinch or scroll to zoom, and tap any row to see its runs of blocks, like "3 blocks, gap 11, 3 blocks". On a keyboard, the arrow keys move the plan, plus and minus zoom, and the square brackets step through rows.
Switch to the Builder's guide to see the edge pattern and a checklist of every row. Your checkmarks are saved in this browser for each shape, so you can close the page and carry on later.
How the circle is worked out
A block is part of the circle when its center sits inside the true circle of the size you chose. That gives the roundest shape a block grid can hold, and it is perfectly symmetrical in every direction.
The thin outline keeps only edge blocks and drops doubled corners, so each block on a curve touches its neighbors at the corners and no block is wasted. The thick outline keeps every block that touches the outside, even at a corner, which closes every diagonal gap.
Reading the edge pattern
Players build circles by counting steps along the edge. Start at the top middle, lay the top row centered, then step down one block and out one block for each number in the pattern. The last number is the straight run down the side.
For circles the pattern reads the same forwards and backwards, so you only need to remember the first half of it: one eighth of the circle. A 21-block circle, for example, goes 7, 2, 1, 1, 1, 2, 7.
Tips for big builds
Mark the middle first. On odd sizes it is one block, shown with an amber outline. On even sizes it is the corner where four blocks meet, shown with an amber dot.
Lay the outline with a cheap block like dirt or wool, check it from above, then swap in your real material. The strong grid line every five blocks makes counting long runs easier.
Building a dome or a tower? The sphere generator shows every layer of spheres, domes and cylinders.