Measurement and the Ayadi System in Vastu: Explained, Not Computed

Ayadi is a traditional method of checking whether the measurements of a building are auspicious. The dimensions are converted into the old units, run through a set of calculations that leave remainders, and each remainder is read against a table of qualities such as aya (gain), vyaya (loss) and yoni (a symbolic animal). This page explains the idea and shows what the pieces are. It does not give a formula to calculate, because the formulas differ from text to text and we could not confirm one in a source we read.

Why the texts care about measurement

The Vastu texts treat measurement as part of the design and not as a separate matter. The Manasara has an early chapter on it, and the treatise deals with units and proportions before it turns to site and structure. In our reading, measure in this tradition has three jobs: it fixes the size of a building so it is in proportion, it connects the building to ritual, and it keeps the craftsmen of a project working to one standard.

The units were taken from the human body. The angula is the width of a finger, the hasta is the forearm, usually 24 angulas, and larger units such as the danda are built from those. Tradition describes smaller units too, each a fraction of the one above, down to a notional atom. This is how shilpa texts are generally described, and the exact table varies by text.

What ayadi is

Ayadi takes its name from the first of its parts, aya, and means roughly “aya and the rest”. It is a set of checks on the measurements of a house or other building, used mainly in the south Indian craft tradition and, by report, still used by traditional builders in parts of the south such as Kerala. Different sources list between six and eight parts.

The eight yonis, as commonly given, are the flag, smoke, lion, dog, bull, donkey, elephant and crow. Some are counted as favourable and some as not. The qualities reflect the culture’s symbolism and have no practical measure behind them.

How a calculation works in outline

Without giving a rule, the structure is this. Take a dimension of the building, usually the length and the breadth, sometimes the perimeter or the area, in the traditional unit. Multiply by a number, divide by another, and keep the remainder. The remainder points to a row in a table. Do it again with a different multiplier and divisor for each part.

The divisors follow the size of the set: eight for the yonis, seven for the weekdays, twenty-seven for the nakshatras, thirty for the tithis. This is simply because a remainder can only fall within that range. To show the arithmetic of a remainder, and only that: dividing 29 by 8 leaves 5. That is not an ayadi calculation. It shows why an answer always lands somewhere between zero and the divisor.

Why this site does not give a formula

Three reasons, all of them practical.

1. The formulas differ. Texts and teachers give different multipliers and different divisors for the same part, and a result calculated from one is not the result from another.
2. The unit matters. The method was built for hastas and angulas. A flat measured in square feet and run through a calculator gives a remainder that the classical method never intended. A change of an inch can move the result.
3. We could not confirm one. We have not read the chapters of the south Indian treatises in which the system is set out, so we cannot give a verified procedure, and an unverified one would be worse than none.

If you meet an online ayadi calculator, treat it as one reading of one school, applied with modern units. Its answer is not a verdict.

What the system is used for

• New construction. Ayadi was a design check, applied when a building was being proportioned. A designer could adjust a dimension slightly until the numbers were favourable.
• Traditional building. It is still part of the working knowledge of some temple and house builders.
• Not for existing homes. An existing flat has dimensions that are fixed. A claim that your flat’s ayadi is wrong is a claim about a building that no one can resize.

Classical and modern

What cannot be changed, and what helps

You cannot change the dimensions of a built home, and nobody should break a wall to fix a remainder. No text we read asks for it. If you are about to build or buy an under-construction home, the best advice is to ask the architect early whether the proportions can be adjusted by a small amount at the drawing stage, since that is the only point at which it costs nothing.

What helps is a sense of proportion in the ordinary meaning of the word. Rooms that are neither very long and thin nor very narrow, ceilings of a comfortable height, doors and windows in sensible ratios, and enough floor for the people who live there are the things a good designer already asks for. The plot shape guide covers the shape of a site, and the Manasara page describes the treatise on which part of this subject rests.

How to question an ayadi reading

1. Which text and which version of the formula do you use?
2. In what unit did you measure, and which walls did you count?
3. What do you propose I do, and does it involve building work?
4. Is it a classical result or a modern calculator’s?

A teacher who can answer is worth listening to. One who cannot should not be asked to correct your home. The method page gives the standard this site applies, and the mandala guide shows how the grid fits with measurement.

Frequently asked questions