40 block circle in Minecraft

How to use it

1. Check the grid and the block count in the tool.
2. Open the row by row guide and start at the top row.
3. Place each row as written: skip the gap, then place the run. Only the top 20 rows are listed, the rest is a mirror image.
4. Download the PNG if you want to keep it open next to the game.

The 40 block circle in numbers

Forty blocks is a landmark size: a cathedral rotunda, a big silo or a round city wall segment. Plan the materials first, the thin wall alone takes hundreds of blocks per layer.

The outline of a circle 40 blocks wide is made of 112 blocks. That is 9 per cent of the 1,264 blocks in the full disc, so a ring is far cheaper than a floor. The ideal area of a circle with this diameter is about 1,257 square blocks, and the filled version differs from that by 0.6 per cent. The circumference of the ideal circle is about 125.7, for comparison.

Row by row guide for the top half

Start at the top row. Each line says how many empty blocks to leave from the left edge and how many to place. When a line has two runs, leave the gap between them empty. Rows below the middle repeat the same lines in reverse order.

1. skip 16, place 8
2. skip 12, place 4, skip 8, place 4
3. skip 10, place 2, skip 16, place 2
4. skip 9, place 1, skip 20, place 1
5. skip 7, place 2, skip 22, place 2
6. skip 6, place 1, skip 26, place 1
7. skip 5, place 1, skip 28, place 1
8. skip 4, place 1, skip 30, place 1
9. skip 4, place 1, skip 30, place 1
10. skip 3, place 1, skip 32, place 1
11. skip 2, place 1, skip 34, place 1
12. skip 2, place 1, skip 34, place 1
13. skip 1, place 1, skip 36, place 1
14. skip 1, place 1, skip 36, place 1
15. skip 1, place 1, skip 36, place 1
16. skip 1, place 1, skip 36, place 1
17. place 1, skip 38, place 1
18. place 1, skip 38, place 1
19. place 1, skip 38, place 1
20. place 1, skip 38, place 1

The filled disc has rows of these widths from the top: 8, 16, 20, 22, 26, 28, 30, 32, 32, 34, 36, 36, 38, 38, 38, 38, 40, 40, 40, 40. Mirror them for the lower half.

Symmetry and straight edges

The diameter is even, so there is no centre block. The middle is a two by two square, and the circle has two middle rows and two middle columns. Mark the two centre lines before you start. The longest straight run is 8 blocks. Long flat runs make a circle look squarer, and short ones make it look rounder, which is why sizes like 32 and 50 look a little different from 40 even though they are close.

Block counts for walls of different heights

A round tower or wall repeats the thin outline layer after layer. These are the totals for a 40 block wide wall.

Building it without mistakes

Place four marker blocks, one at each side, then fill in the runs between them. The two middle blocks on each side are the ones that line up with the centre lines. Build one quarter, check it against the guide, and copy it to the other three by mirroring. Count your first row before you build the rest, a single wrong skip shifts the whole curve.

For a roof or a floor, switch the tool to Filled. For a wall with no diagonal gaps, which matters for moats, pens and sealed rooms, switch to Thick and expect 44 extra blocks per layer.

Other circle sizes

• 5
• 7
• 9
• 10
• 11
• 12
• 13
• 15
• 16
• 20
• 25
• 30
• 32
• 40
• 50
• 64
• 100

For ovals or any size not listed, use the circle generator. To turn a circle into a ball, try the sphere generator, or the stack calculator to turn a block total into chests.

Block counts on this page are computed by the generator and are the same in every version of the game. BlockShapes is not affiliated with Mojang or Microsoft.