Enter the length and breadth of a building and this tool works out the classical ayadi checks one by one: aya and vyaya, the yoni, the nakshatra, the weekday and the lunar day. Every step of the arithmetic is shown, so you can repeat it by hand. The formulas come from the Manasara, and where texts differ the page says which one is used. Nothing here is a verdict on a home, and nothing is predicted.
What ayadi is
Ayadi is a traditional design check from the south Indian craft treatises. A dimension of a building is converted into whole units, multiplied by a fixed number and divided by another, and the remainder is read against a list: twelve ayas, ten vyayas, eight yonis, twenty-seven nakshatras, seven weekdays, thirty tithis. Each item in a list is counted favourable or not by the text. The explanatory page on measurement and the ayadi system describes the idea and the units, and the page on the Manasara describes the treatise.
The formulas used
This tool uses the Manasara’s usual set, as P. K. Acharya gives it in his English translation of 1934 and in his dictionary entry on the six formulas.
| Check | Measure | Multiply by | Divide by | Remainder is |
|---|---|---|---|---|
| Aya | Length | 8 | 12 | One of twelve ayas |
| Vyaya | Breadth | 9 | 10 | One of ten vyayas |
| Riksha | Length | 8 | 27 | A nakshatra, counted from Ashvini |
| Yoni | Breadth | 3 | 8 | An animal, from the flag to the crow |
| Vara | Circumference | 9 | 7 | A weekday, counted from Sunday |
| Tithi | Circumference | 9 | 30 | A lunar day |
The circumference is worked out as twice the length plus the breadth. The Manasara also gives an amsha formula (circumference times 4, divided by 9) that replaces tithi for some classes of building. The tool shows its number but gives no verdict, because the list of nine could not be read in the copy used.
Where texts differ: another chapter of the Manasara gives different multipliers by class of building, for example length times 6, 7 or 8 for aya, and the Bimba-mana and the Agamas differ from the Manasara too. The divisors agree in every case. A calculator that uses another set of multipliers gives another answer, and neither is wrong, since they follow different texts. This tool uses the usual set above and does not mix them.
How the favourable and unfavourable remainders are read
For aya and vyaya together, the Manasara says that no remainder in either is favourable. Otherwise the aya remainder should be greater than the vyaya remainder, and if the two are equal there is no defect. If the aya is smaller, the text does not favour it. The tool counts these as one test.
For the yoni the favourable animals are the flag, the lion, the bull and the elephant. For the nakshatra Acharya renders the rule as odd-numbered, or full, nakshatras being favourable and even-numbered ones not. For the weekday the favourable days are Monday, Wednesday, Thursday and Friday. For the tithi the new-moon day, the eighth and the ninth are avoided and the rest are accepted.
Three of these needed a choice the text does not spell out, and the result says so each time they apply. A remainder of zero in the yoni, riksha, vara or tithi is read as the last item of its list. The thirty tithis are taken as the bright half first and then the dark half. These are this site’s readings.
Units matter
The method was built for whole units counted in the old measures, and it is sensitive to them. A change of one unit can move every remainder. So the tool asks you to choose whether to count in whole angulas or whole hastas, rounds your measure to the nearest whole unit and shows the count it used. The conversion, 1 angula as 0.75 inch (1.905 cm) and 1 hasta as 24 angulas, is a convention chosen for this tool, because the texts and the regions differ on the exact size. If your builder works in a different standard hasta, enter your measure in hastas directly.
What the result is for
Ayadi was a check made while a building was being proportioned. A designer could nudge a dimension by a unit or two until the numbers agreed, at no cost. For that reason the tool lists nearby measures that pass every test when yours do not. It is a drawing-stage aid.
It is not a judgement on a home that already stands. A built house has fixed dimensions, and no text read for this site asks anyone to break a wall to change a remainder. The qualities attached to each remainder, such as a symbolic animal, are the symbolism of the craft tradition and have no practical measure behind them. If you are planning to build, the better questions are about proportion in the ordinary sense: daylight, ventilation, ceiling height and usable floor. An architect can answer those, and also whether a small change at the drawing stage is possible.
Frequently asked questions
↳ Which text is the ayadi calculator based on?
The Manasara, in P. K. Acharya's English translation of 1934 and his dictionary entry on the six formulas. The tool uses the usual set of multipliers and divisors given there and states where other chapters and treatises differ.
↳ Why do I get different answers in angulas and in hastas?
The method works on whole numbers, so rounding to a different unit changes the measure, and the remainders move. That is a property of the method. Use the unit your designer or builder works in.
↳ Does a failed test mean my home is unlucky?
No. Ayadi was a design check applied while a building was being drawn. It says nothing about a finished home, and no text read for this site asks for any change to one.
↳ Should aya be greater than vyaya?
Yes, in the Manasara's rule as Acharya gives it: a greater aya and lesser vyaya are favoured, equal remainders carry no defect, and no remainder in either is favourable. It is the text's rule, shown as tradition.
↳ Can I use this to fix the size of a room or a flat?
It was meant for the proportions of a whole building at the drawing stage. For an existing flat or room the dimensions cannot be changed, and nothing should be rebuilt to alter a remainder.