Missing corners in an L-shaped home
Published 2026-08-20
A missing corner is a part of the nine-square bagua grid that falls outside the walls of your home. A rectangle contains all nine areas. An L-shape cannot, so one or two of them end up outside the footprint, and which ones they are depends entirely on which wall your front door is in — because the grid is lined up with that wall and rotates with it.
The same physical bite out of the same building is a different area for a different door position, so a source that tells you which corner is missing without asking where you come in has not finished the calculation.
Which tradition this is
The missing-corner idea, and the life-area names that go with it, belong to the three-door bagua — the method taught in the West since the 1980s, often called BTB or Black Sect, which lines the nine squares up with the front door and never uses a compass. Our bagua map computes that version.
Eight Mansions, the compass school that drives the rest of this site, also looks at building shape, but it would name an absent corner by its bearing rather than by a life area, so it does not produce the same list. We do not compute that reading, and you should not assume the two agree.
The same cut-out, four different answers
Here is one plan run four times, changing nothing but the door wall. The home is 12 m by 9 m with a 4 m by 3 m bite taken out of one corner — a garage-sized notch. Reading the plan on screen with the bite at the bottom right:
| Front door is in the | Area that falls outside |
|---|---|
| Bottom wall (the same wall as the notch) | Helpful People |
| Left wall | Love |
| Top wall | Wealth |
| Right wall | Knowledge |
Four different answers from one building. Nothing about the walls changed; the grid turned. If you have read that a missing corner in the back right is bad for your relationships, that statement is carrying an unstated assumption about where your front door is.
How the grid is laid down
Two mechanical details decide everything the tool reports.
The nine cells are cut from the bounding rectangle, not from the L-shape. Width is divided by three and depth is divided by three, so every cell is the same size and the missing part of the plan still has grid over it. On a 12 m by 9 m plan each cell is 4 m by 3 m, which is 12 square meters, whether or not any of it is inside the walls.
The grid is then rotated so that the door wall carries the near row. In this system the front door always opens into the career strip, and the far-left corner as you walk in is always the wealth area. Everything else follows from those two anchors.
Missing, clipped, or not worth mentioning
A cut-out rarely lands neatly on a cell boundary, so the tool sorts each cell into three states rather than two.
- Missing — essentially none of the cell is inside the footprint. The tool uses a threshold of a tenth of one percent remaining, so in practice this means the cut swallowed the whole cell.
- Clipped — more than 10% of the cell’s area is outside the walls, but some of it is inside.
- Present — 10% or less of the cell is outside. Nothing is reported at all.
That 10% cutoff is a number we chose, not one the tradition supplies, and you can disagree with it. What it does is stop a small notch from being announced as a missing life area. Worked through on the 12 m by 9 m plan, where each cell is 12 square meters, a tenth of a cell is 1.2 square meters. A square notch 1.09 m on a side removes 1.19 square meters, which is 9.9% of the cell, and the tool says nothing. Widen the notch to 1.1 m on a side and it removes 1.21 square meters, which is 10.1%, and the cell is reported as clipped. The difference between silence and a warning is one centimeter, which tells you how much weight to put on a borderline case.
The threshold cuts the other way too, and the tool is deliberately reluctant at the top end. On a 10 m by 8 m plan, a cut-out 3 m wide by 2.5 m deep leaves only 16% of the wealth cell inside the walls. The tool still calls that clipped rather than missing, and it prints the percentage, because “84% outside” is a more honest sentence than “your wealth area is gone”.
Larger bites take whole areas out cleanly. On the same 12 m by 9 m plan, a cut 8 m wide and 3 m deep along the far edge, with the front door in the near wall, puts both Fame and Love entirely outside the footprint — two areas, not one.
Where you draw the footprint changes the answer
The tool has no opinion about what counts as part of your home. It uses the outline you type in. An attached garage, a covered porch, a screened patio, a bay window — each of those either is or is not part of the footprint, and you decide before any calculation happens. Include the garage and the plan may be a rectangle with nothing missing. Exclude it and the same building has a missing corner.
That is not a flaw we can code around. It is a judgment that sits upstream of the arithmetic, and it is the largest single source of two people getting different bagua maps for the same house. If you want the reading to be reproducible, write down what you counted.
What to do about one
Here the honest answer is short. Practitioners in this tradition suggest mirrors on the inside walls that face the gap, lighting or planting on the outside boundary to imply the missing corner, and sometimes a physical extension. None of those suggestions has a test attached, and we are not going to tell you what any of them does to your finances or your relationships — see method and assumptions.
Which of the nine squares the gap falls in does change what the tradition asks you to put there — a different element for each of the eight outer sectors, and a different person in the household attached to each. That table is in The Home Feng Shui Walk-Through, along with the rest of the shape rules: trapezoid plans, projecting wings, and what belongs in the center.
If you also want the compass reading of the same building, that is a separate question with a separate tool, and two things are called a bagua map explains why the two answers will not match.