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MC Calc

Circle & Sphere Generator

Java Edition

Pick a size and get a block-by-block plan for a circle, ellipse, sphere or dome — with how many blocks go in each row and layer, and the total you need to gather.

Shape

Blocks

Blocks
80
1 stacks + 16
Size
21×21
circle

Plan

Dashed lines mark the centre; darker lines every 5 blocks.

Blocks per row
  1. Row 17 · 8–14
  2. Row 26 · 6–8, 14–16
  3. Row 34 · 5–6, 16–17
  4. Row 44 · 4–5, 17–18
  5. Row 54 · 3–4, 18–19
  6. Row 64 · 2–3, 19–20
  7. Row 72 · 2, 20
  8. Row 84 · 1–2, 20–21
  9. Row 92 · 1, 21
  10. Row 102 · 1, 21
  11. Row 112 · 1, 21
  12. Row 122 · 1, 21
  13. Row 132 · 1, 21
  14. Row 144 · 1–2, 20–21
  15. Row 152 · 2, 20
  16. Row 164 · 2–3, 19–20
  17. Row 174 · 3–4, 18–19
  18. Row 184 · 4–5, 17–18
  19. Row 194 · 5–6, 16–17
  20. Row 206 · 6–8, 14–16
  21. Row 217 · 8–14

How it works

A block belongs to the shape when its centre is inside the ideal circle (or ellipse, or sphere). Even sizes are centred between blocks, odd sizes on a block, so both look symmetric.

Outlines keep only the blocks on the edge. Thin outlines are the minimum: blocks may touch only at their corners. Thick outlines fill those corners so every block shares a side with the next — use them for walls you can't walk through diagonally.

Spheres are built layer by layer: use the layer slider and place each slice in turn. A dome is the top half of a sphere.

Formulas

Inside test
((x + ½ − w/2) ÷ (w/2))² + ((z + ½ − h/2) ÷ (h/2))² ≤ 1
Thin / thick outline
inside and a side neighbour (thin) / any neighbour incl. diagonals (thick) is outside
Approximate totals
filled circle ≈ π r² · sphere ≈ 4/3 π r³

FAQ

Should I use an odd or even diameter?

Odd diameters have a single centre block, which makes it easy to start from a marker. Even diameters are centred on a corner and look slightly rounder at small sizes.

What's the difference between thin and thick?

Thin outlines connect diagonally (fewer blocks, mobs and players can't pass the corners but light and water can). Thick outlines connect side to side, which is better for walls and water tanks.

How do I build a sphere?

Pick “Sphere”, then go through the layers from 1 upward. Each layer is a circle; place it, go up one block and switch to the next layer.

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