Worked example: the 21 × 9 oval
This is the shape most people arrive here wanting — a stretched ring for a track, a canal, a stadium infield or a long ornamental pond. The outline is 44 blocks; filled in solid it is 149 blocks (2 × 64 + 21), so the interior costs 105 blocks on top of the rim. Here it is at full size:
......XXXXXXXXX...... ...XXX.........XXX... .XX...............XX. X...................X X...................X X...................X .XX...............XX. ...XXX.........XXX... ......XXXXXXXXX......
Look at the top edge: 9 blocks in one straight run, then the curve steps away in groups of 3, then 2, then 1. That long flat top is not a rendering compromise — it is what a 2.3:1 ellipse genuinely looks like on a block grid, and it is the first thing you should place, because it gives you a straight reference edge for the rest of the shape.
As a sanity check, the ellipse area formula πwh/4 gives 148 against the real filled count of 149 — a gap of 0.4%. Close enough to plan a shopping trip with, not close enough to place blocks with.
How flattening changes the shape
Here is the part that is hard to guess in advance. Keeping the width fixed at 15 and reducing only the height, watch what happens to the straight run along the top:
| Size | Ratio | Top flat run | Outline blocks |
|---|---|---|---|
| 15 × 15 | 1.00:1 | 5 | 40 |
| 15 × 13 | 1.15:1 | 5 | 36 |
| 15 × 11 | 1.36:1 | 7 | 36 |
| 15 × 9 | 1.67:1 | 7 | 32 |
| 15 × 7 | 2.14:1 | 7 | 32 |
| 15 × 5 | 3.00:1 | 9 | 28 |
| 15 × 3 | 5.00:1 | 11 | 26 |
The flat run grows steadily as the shape flattens, from 5 blocks on the circle to 11 on the most extreme ellipse — at which point the "oval" is essentially a straight line with rounded ends. Meanwhile the outline count barely moves. This is the practical trade-off in oval design: flattening a shape does not save you many blocks, it just converts curve into straight edge. If the silhouette matters more than the footprint, keep the ratio under 2:1.
Preset sizes and what they suit
Exact counts, computed by the same code as the tool. The use column is a suggestion, not a rule.
| Width × Height | Ratio | Outline | Filled | πwh/4 | Typical use |
|---|---|---|---|---|---|
| 9 × 5 | 1.80:1 | 20 | 37 | 35 | Small pond or rug |
| 11 × 5 | 2.20:1 | 24 | 47 | 43 | Decorative table top |
| 13 × 7 | 1.86:1 | 28 | 75 | 71 | Round-ended room |
| 15 × 9 | 1.67:1 | 32 | 107 | 106 | Small arena floor |
| 16 × 8 | 2.00:1 | 32 | 100 | 101 | Exactly one chunk wide, half as deep |
| 21 × 9 | 2.33:1 | 44 | 149 | 148 | Running track infield |
| 24 × 12 | 2.00:1 | 52 | 232 | 226 | Amphitheatre floor |
| 31 × 15 | 2.07:1 | 68 | 369 | 365 | Large stadium bowl |
Each size links through to the main generator with those dimensions already loaded.
Building an oval accurately
The method is the same as for a circle, and it still works because the ellipse is symmetric on both axes. Place the four flat runs first — top, bottom, left and right — then build one quarter and mirror it three times. The difference with an oval is that the top and bottom runs are long while the left and right runs are short, so the two pairs of anchors are not interchangeable. Measure the long axis first; an error there is much more visible than the same error on the short axis.
For an oval tower, multiply the outline count by the height. A 21 × 9 tower 10 blocks tall is 44 × 10 = 440 blocks. For an oval floor, use the filled count. If you want a wall with a floor, add both and subtract nothing — they occupy different Y levels.
Related tools
- Equal width and height? The Minecraft circle generator is the same tool with the dimensions locked together, and its guide covers the rasterization rule in detail.
- Need a reference table rather than a slider? The Minecraft circle chart lists every diameter from 5 to 32 with previews and block counts.
- Building in three dimensions? The sphere generator and the dome generator slice round shapes into per-layer plans.