CodeKitHubWhat Is This Tool?
A pixel circle is the standard technique for approximating a circle on any square grid — video games, pixel art, and cross-stitch patterns all use the same underlying idea: for each grid cell, mark it "in" the circle if its distance from the center is within the target radius, and "out" otherwise. Because Minecraft's world is fundamentally a 3D grid of 1×1×1 blocks, this same 2D grid technique is exactly what's needed to lay out a circular floor, tower cross-section, or dome ring for a build.
This tool computes that grid directly: enter a diameter, and it marks every cell within that radius of the center, rendering a visual block-by-block preview plus a copyable text pattern using # for a block and . for empty space, so you can follow it in-game row by row.
It also supports a hollow "outline" mode, which keeps only the cells on the boundary of the filled circle — the layout you need for a ring-shaped wall or a circular window frame rather than a solid disc, and one that uses dramatically fewer blocks for large diameters.
Why Use It?
- You're three layers into building a castle tower freehand and just noticed one side bulges out more than the other — instead of tearing it down, generate the correct grid first and rebuild it symmetrically from a known-good pattern.
- You're about to fly to the Nether or a far-off village to mine enough stone for a dome roof and don't want to make two trips — check the exact block count first so you gather the right amount in one run.
- You're building a circular window into a tower wall and a solid disc would block all the light — switch to outline mode to get the thin ring pattern that leaves the center open.
- You're deciding between a 16-block and a 24-block diameter for a base's central silo and want to see how much rounder the larger circle looks before committing blocks and floor space to it.
- 100% local: the grid is generated entirely in your browser with no data sent anywhere.
How to Use
- Enter the diameter you want, in blocks (3 to 64).
- Choose Filled for a solid disc, or Outline for a hollow one-block-thick ring.
- The grid preview updates instantly, along with the exact block count needed.
- Click "Copy text pattern" to copy a row-by-row # / . grid you can reference while building, or follow the visual grid directly.
Example
Input
Diameter: 16, Mode: OutlineOutput
40 blocks neededA filled 16-block circle needs 188 blocks, but the same diameter in outline mode needs only 40 — outline mode is dramatically more block-efficient for large rings, walls, and window frames where you don't need a solid interior.
Filled vs. outline block counts
Outline mode's block savings grow dramatically as the diameter increases, since a ring's block count scales with its circumference while a filled disc's scales with its area.
| Diameter | Filled blocks (approx.) | Outline blocks (approx.) |
|---|---|---|
| 8 | 44 | 20 |
| 16 | 188 | 40 |
| 32 | 772 | 88 |
| 64 | 3,168 | 176 |
Related tools
For other grid, pattern and measurement tools, try these.
→ CSS Background Pattern Generator · GCD & LCM Calculator · Unit Converter
Building a dome layer by layer
A dome is really just a stack of circles that shrink as you go up, similar to how a real-world dome's cross-section narrows toward the top. This tool doesn't generate the whole 3D shape at once, but building one is straightforward once you break it into individual layers.
- Start at the base with your largest diameter — for a 16-block-wide dome, that's your first outline or filled layer.
- Move up one block and reduce the diameter by roughly 2–4 blocks per layer, generating a new grid for each one.
- Use Filled mode for a fully solid dome, or Outline mode per layer if you want a hollow interior you can stand inside.
- The top 2–3 layers usually shrink faster than the rest, since a real dome's curve steepens near the peak — feel free to eyeball the final cap rather than generating a diameter-3 grid for it.
Frequently Asked Questions
Why isn't there a perfectly smooth circle option?
Minecraft's world is built entirely from 1×1×1 blocks on a grid, so no in-game structure can be a mathematically smooth circle — every circular-looking build is actually a pixel-grid approximation. This tool generates that approximation directly, using the same distance-from-center technique used for pixel art and pixel circles generally.
What's the difference between Filled and Outline mode?
Filled mode marks every grid cell within the target radius, producing a solid disc — useful for a floor or a flat circular platform. Outline mode keeps only the cells on the boundary of that disc, producing a one-block-thick ring — useful for a tower wall, window frame, or any structure that shouldn't be solid, and it uses far fewer blocks.
Why does the block count matter?
For a large build, knowing the exact block count in advance means you can gather precisely the right amount of material in one trip instead of running out mid-build or over-mining. It also lets you compare the material cost of different diameters or filled-vs-outline before deciding what to build.
Can I use this for domes and roofs, not just flat circles?
Yes — a dome is typically built as a stack of circular rings of decreasing diameter, and a conical roof works the same way. Generate the grid for each diameter in your dome or roof's cross-section, one layer at a time, working from the largest ring at the base to the smallest at the top.
Is anything I enter sent to a server?
No. The circle grid is computed entirely in JavaScript in your browser. Nothing is uploaded or stored.
What's the smallest and largest diameter this supports?
The tool accepts diameters from 3 to 64 blocks. Very small circles (3–5 blocks) look more like a square or diamond than a circle since there's so little grid resolution to work with — larger diameters approximate a true circle much more closely.
How do I read the # / . text pattern while building in-game?
Each row of the pattern corresponds to one row of blocks in your world. Place a block everywhere you see a #, and leave the space empty everywhere you see a . — working through the pattern row by row keeps you from losing your place on a large grid.
Can I build an oval or ellipse with this tool instead of a perfect circle?
No — this generator produces true circles only, based on a single diameter. For an oval shape you'd need to stretch a circle grid manually by duplicating rows or columns, which this tool doesn't automate.
Does the outline mode ever produce gaps or double-thick spots?
The outline is calculated to stay a consistent one block thick around the boundary, though at very small diameters the geometry can force a slightly thicker spot in places — this is a natural limitation of approximating curves on a square grid, not a bug in the pattern.
Can I use the same grid pattern for a floor design or art project, not just walls?
Yes — the grid pattern is just a block layout, so it works equally well as a circular floor mosaic, a pixel-art circle in wool or concrete, or any other flat design, not only for towers and domes.