Aaya and Ayadi in Vastu: What the Calculation Says, and What It Can Tell You About a Flat

Short answer. Aaya is a number derived from a building's perimeter, not from which way it faces or where its rooms sit. You measure the length and width, add them, double the result to get the perimeter, convert that to a traditional unit, and take six remainders from it — Aaya, Vyaya, Yoni, Vara, Nakshatra and Tithi, together called the Ayadi Shadvarga. Practitioners read it as one comparative test (Aaya should exceed Vyaya) plus one categorical one (the Yoni should be odd). For a flat you are buying, the honest verdict is that Ayadi is a design-time system: it governs dimensions someone chooses before the walls go up, and there is almost nothing you can do with it afterwards. It also says nothing at all about where your kitchen is.

The six values, and where each comes from

The calculation works on the perimeter, usually written P. Our Aaya calculator converts your feet or metres into angulas at 1 angula = 3/4 inch, then applies six fixed multiplier-and-divisor pairs and keeps the remainder. Where a remainder comes out as zero, convention reads it as the full divisor.

Two rules do most of the work. Aaya should be greater than Vyaya — the test is comparative, not absolute, so a "high Aaya" on its own means nothing. And the Yoni should be odd: the four odd yonis are Dhwaja (flag), Simha (lion), Vrishabha (bull) and Gaja (elephant), and the four even ones — Dhooma, Shwana, Khara and Kaka — are the ones traditionally avoided for dwellings.

A detail worth knowing before you go looking for a "good Aaya number": under this multiplier set the Aaya remainder can only ever be 4, 8 or 12. Eight and twelve share a factor of four, so no other value is arithmetically reachable. Any rule you have read that Aaya itself should be an odd number belongs to a different convention, because with these multipliers it is impossible.

Why almost every flat fails the Yoni test on paper

Here is something none of the Ayadi pages online will tell you, and it falls straight out of the arithmetic.

Suppose a room or a flat measures a whole number of feet on each side — say 30 ft by 24 ft. The perimeter is 2 × (30 + 24) = 108 ft, which is 1,296 inches, which is 1,728 angulas at 3/4 inch each. Now look at what that does to Yoni: 1,728 × 3 = 5,184, and 5,184 ÷ 8 leaves remainder 0, read as 8 — Kaka, the crow. An even yoni.

That is not bad luck with one example. Any rectangle whose sides are whole feet gives a perimeter of 32 × (length + width) angulas, which is always a multiple of eight, which forces the Yoni remainder to zero every single time. Measured in whole feet, no flat can ever pass the odd-Yoni test — not because the flat is defective, but because of the unit you measured it in. Traditional builders set out in angulas and hasta precisely because the remainders shift with every single angula, and a flat marketed to you as "10 × 12" is not a measurement at that resolution.

So if you have run your apartment through an Ayadi calculator and been told it is unfavourable, check what you typed in before you worry. The result may be telling you about arithmetic rather than about your home.

Does Ayadi matter for a flat you are buying?

Three things follow from the above, in order of how much they should affect a purchase decision.

1. You cannot act on it. The way practitioners fix Ayadi is by nudging one side by a few millimetres until the perimeter lands on a favourable remainder — a one-angula change in perimeter is about 9.5 mm on a single wall. That is a drawing-board correction. In a finished apartment there is no wall you can move by 9.5 mm, and the slab, the columns and the neighbouring unit are not yours.
2. It needs dimensions you probably do not have. The calculation is sensitive to the angula. You would need the as-built internal dimensions to the inch, not the brochure's carpet-area figure, before the answer means anything.
3. It is a proportion test, not a placement test. This is the important one, and it is where most confusion starts.

Ayadi grades the size and shape of a building. It has nothing to say about which direction your main door faces, where the kitchen sits, or whether the toilet is in the north-east. Those are a different classical system entirely — the eight-zone placement model — and that system is the one that produces the advice you have actually read in vastu articles.

The two get tangled because Yoni carries a direction label: yoni 8, Kaka, is tagged north-east at 45°. That is a classification of the building's orientation class under the Ayadi system, and it is not a statement that the north-east is a bad place for things. In the placement model the north-east is the single best zone there is — our own table scores a main entrance in the north-east at 100, the top of its row, and a pooja room there at 100 as well. The two systems are answering different questions and neither overrules the other.

What to check instead, for a built flat

If you are assessing an apartment rather than designing a house, the placement side is where every decision you can still make actually lives — which room becomes the master bedroom, which corner the shrine goes in, whether a defect is worth fixing or worth walking away from. That is what our free check grades: upload your floor plan for a free Vastu check, confirm north and the room labels, and you get each zone scored and an overall number. If you want to see how the zone arithmetic plays out room by room, the 2BHK and 3BHK checklist walks through it in the order the rooms matter.

And if you are at the design stage — a plot, an architect, a plan that is still changing — then Ayadi is genuinely available to you, and it costs nothing to check. That is exactly the case the Aaya calculator is built for: it prints every multiplication, division and remainder, and shows which small changes to a single side would land the perimeter on a favourable value. Use it while the dimensions are still a decision. Afterwards, it is history.