A 15 block circle in Minecraft is 40 blocks as a hollow ring one block thick, and 177 blocks filled in. Fifteen is odd, so the ring closes on a single centre block, and it is small enough that the whole layout fits in one picture. A 15x15 circle and a 15 by 15 circle are the same thing written differently: a ring 15 blocks across in both directions.
Table of contents
Open Table of contents
The 15 ring, block by block
# is a block and . is empty ground.
.....#####.....
...##.....##...
..#.........#..
.#...........#.
.#...........#.
#.............#
#.............#
#.............#
#.............#
#.............#
.#...........#.
.#...........#.
..#.........#..
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.....#####.....Read it from the top: a flat cap of 5, a step of 2 on each side, a single block, a vertical pair, and then five blocks straight down the side. The bottom half is the top half mirrored, so the rows run 5, 4, then eleven rows of 2, then 4 and 5 again, which adds up to 40.
Placing it starts from the middle. With one centre block down, the outermost blocks of the ring sit 7 blocks away from it in each of the four directions, so count 7 out along each axis, mark those four points, and the flat caps of 5 are centred on them. Highlight Center in the generator draws the same two axes through the blueprint.
To get the same ring on screen, set Diameter to 15 in the circle generator with Fill Mode on Hollow and Border Thickness on Thin. MC Shapes is a free, browser-based set of Minecraft shape generators (circle, oval, sphere and dome) that outputs block-by-block blueprints with exact block counts; it does not export schematic files. If you have not built a circle block by block before, the quarter-and-mirror method is the way to place it: one quarter of this ring is only ten blocks.
Why other charts give a different number
When I searched for this count, the answers ran from 36 to 44. They are not all wrong. A circle drawn on a grid has to decide how its corners step, and two charts that step them differently will count a different ring for the same width. I did not trace which stepping rule each of those charts follows, so I cannot tell you which of them will agree with the grid above.
This generator’s 15 ring steps corner to corner everywhere, which is the thinnest ring that still closes, and that is how it lands on 40. I ran its algorithm for every diameter from 3 to 25 and counted the corner blocks that sit edge to edge with two neighbours. The 15 ring has none. The 13 ring has twelve, which is why a 13 block circle also costs 40 blocks: it is a smaller ring with doubled shoulders.
The rule that follows from this is short: build from one chart, and check your placed count against that chart’s own total.
Counts for every border and fill
| Fill | Border | Blocks | Stacks |
|---|---|---|---|
| Hollow | Thin (1) | 40 | 40 |
| Hollow | Thick (2) | 80 | 1×64 + 16 |
| Hollow | Very thick (3) | 108 | 1×64 + 44 |
| Solid | n/a | 177 | 2×64 + 49 |
A 15 block circle with a Thick border is 80 blocks. With a Very Thick border a 15 block circle is 108 blocks, and filled solid it is 177 blocks. The floor inside a thin 15 ring is 137 blocks, which is the solid count minus the ring.
Its neighbours, all as thin hollow rings from the same generator:
| Diameter | 11 | 13 | 15 | 17 | 21 |
|---|---|---|---|---|---|
| Blocks | 28 | 40 | 40 | 48 | 56 |
The big sibling, at twice the width, is the 31 block circle at 84 blocks.
What a 15-wide ring holds
The 137 blocks of floor inside the ring are a little less than a 12 by 12 room. That is enough for a working interior, and it is the size the round castle and tower guide gives as the smallest keep that fits a spiral staircase with a usable room around it.
Stacked into a tower, each floor of wall is another 40 blocks, so ten layers are 400. Capped with a dome, the dome generator puts a 15-wide hollow dome at 321 blocks and 8 blocks tall. A full hollow sphere on the same diameter is 602 blocks.
What 15 does not do is look smooth from far away. The steps in the grid above are still easy to see, and I would not use it for anything meant to read as a clean curve from across a valley. That is what 31 is for. At 15 the ring is a room, a tower or a fountain basin, seen from close up.
Forty blocks is less than a stack, so this is a ring you can afford to place twice. Set 15 in the circle generator with Highlight Center on, and the grid above is on your screen with its single middle block marked.