How to use it
- Look at the bottom layer in the tool, then use Next to move up.
- Build each layer completely before starting the next one.
- Use the faint outline of the layer below as your guide.
- Stop at layer 31. The layers above the middle mirror the ones below it.
The 31 block sphere in numbers
Thirty one blocks is an observatory, a space station hub or a big arena roof. Build the hollow version and fill the inside only where you need floors.
The solid version holds 15,515 blocks. The ideal volume of a ball this wide is about 15,599, so the blocky version is 0.5 per cent smaller. The hollow shell is 15 per cent of the solid count, which is why almost every sphere you see in a build is hollow.
| Style | Blocks | Stacks of 64 |
|---|---|---|
| Hollow, thin shell | 2,382 | 37 stacks + 14 |
| Hollow, thick shell | 4,130 | 64 stacks + 34 |
| Solid | 15,515 | 242 stacks + 27 |
Blocks in every layer
The table lists the first 16 layers from the bottom. The top half is the same list in reverse. The widest layer, the equator, has 749 blocks when solid and 84 when hollow.
| Layer | Solid | Hollow |
|---|---|---|
| 1 | 45 | 45 |
| 2 | 137 | 92 |
| 3 | 221 | 84 |
| 4 | 293 | 72 |
| 5 | 373 | 80 |
| 6 | 437 | 64 |
| 7 | 497 | 68 |
| 8 | 553 | 72 |
| 9 | 593 | 76 |
| 10 | 641 | 80 |
| 11 | 673 | 80 |
| 12 | 697 | 84 |
| 13 | 725 | 84 |
| 14 | 749 | 84 |
| 15 | 749 | 84 |
| 16 | 749 | 84 |
Centre and equator
With an odd diameter the sphere has one centre block and one equator layer, layer 16. A pillar of 31 blocks through the centre lets you mark every layer. The bottom layer is a small disc of 45 blocks, and the radius grows quickly in the first few layers, then slowly near the middle.
How to build it
Work from the bottom up. Finish each layer, then check it against the faint outline of the one below. For hollow spheres, leave the inside empty and fill only the first layer if you want a floor. Mark the layer numbers on a pillar or a sign so you never lose your place. In survival, collect 37 stacks + 14 for the thin shell, and a few extra stacks of scaffolding or dirt for placing blocks in the air.
Compared with nearby sizes
A small change in diameter changes the cost a lot, because the shell grows with the square of the width. Here is the 31 block sphere next to its neighbours in this guide.
| Diameter | Hollow | Solid | Chests for hollow |
|---|---|---|---|
| 21 | 1,082 | 4,945 | 1 |
| 31 (this page) | 2,382 | 15,515 | 2 |
| 41 | 4,242 | 36,137 | 3 |
Chests are single chests with 27 slots, full of stacks of 64. The hollow 31 block sphere fills 2 of them. A solid one fills 9. If that is more than you want to gather, drop to a smaller diameter or keep the sphere hollow and use the thin shell.
Other sphere sizes
For ellipsoids or sizes not listed, use the sphere generator. For half a sphere, see the dome generator, and use the stack calculator to plan chests.
Height limit information is from the Minecraft Wiki, checked on 25 October 2026. BlockShapes is not affiliated with Mojang or Microsoft.
Frequently asked questions
How many blocks is a 31 block sphere?
A solid sphere needs 15,515 blocks, which is 242 stacks + 27. A hollow one with a thin shell needs 2,382 (37 stacks + 14), and a thick hollow shell needs 4,130.
How many layers does a 31 block sphere have?
31 layers, one for each block of height. The widest layer is the equator with 749 blocks when solid.
Is a hollow 31 block sphere closed?
Yes. The thin shell keeps every block that touches empty space on a face, so it has no holes you could walk through. Corners may touch only at their edges, so choose the thick shell if you need a shell with no diagonal gaps.
Does 31 blocks fit under the build limit?
Yes. The Overworld in Java Edition 1.18 and later is 384 blocks tall, so a sphere of 31 blocks uses 8 per cent of the height.
Which is better, 21 or 31?
A sphere of 21 needs 1,082 blocks hollow, 1,300 fewer than 31. A sphere of 41 needs 4,242 blocks hollow, 1,860 more. Choose by the space you have and the material you can gather.