Method, in full
How your file is calculated
Use these settings to compare positions and period dates with another calculator.
What “accurate” means here
Accuracy of calculation can be checked; accuracy ofprediction cannot, and we do not claim it. What we claim is narrow: every position and date in your file comes from stated settings, and the same settings reproduce the same numbers in other professional software. The checklist below is the one to hold any kundli to.
- Are the settings stated? Ayanamsa, house system, node type. If a report does not say, you cannot compare it.
- Is the birth time tested? A few minutes can change the rising sign and shift period dates. See the birth time check.
- Do the dates reach the day? Period dates should be printed with their boundaries, not given as years.
- Does it say where it is unsure?
Positions
- Planetary positions come from the Swiss Ephemeris, the same astronomical library used in professional practice.
- The zodiac is sidereal, using the Lahiri ayanamsa in its True Chitrapaksha form (anchored to the star Spica).
- The lunar nodes are the mean nodes. Ketu is always exactly opposite Rahu.
- Positions are true geometric longitudes at your birth moment, converted from your local clock time using the time zone in force at that place on that date.
- Retrograde motion is marked where it applies.
Houses and cusps
- Readings are given in whole-sign houses, the classical Vedic frame: the rising sign is the first house, the next sign the second, and so on.
- Where a cusp-based reading is needed — the KP layer — the cusps come from a single unequal house system used consistently throughout the file. The house system is kept consistent within each table.
Divisional charts
- The divisional charts (D-2 through D-60) are computed from the same longitudes by the classical division rules, not re-derived from a different chart.
- Special points — the arudhas, the special lagnas, the sahams — are computed in one frame per table, and the file tells your assistant which table is which. A point can legitimately fall in one sign by degree and another by sign-based reckoning; that is a difference of frame, not an error.
Periods
- The main period system is Vimsottari, seeded from the Moon’s exact position at birth, with the standard year lengths (Ketu 7, Venus 20, Sun 6, Moon 10, Mars 7, Rahu 18, Jupiter 16, Saturn 19, Mercury 17 — 120 in all).
- Periods are printed to three levels for your whole life. Below that, your assistant divides the printed period in the same proportions. Those finer boundaries can differ by a few days from another calculator, and your file instructs the assistant to say so rather than pretend to a precision it does not have.
- The annual chart is the moment the Sun returns to its exact birth longitude. The lunar-return chart is the moment the Sun–Moon angle at your birth recurs within the same lunar month.
Your birth time
- Every file states how far your birth time can move before the rising sign changes, before the D-9 rising sign changes, and how far a minute of error shifts your period dates.
- Your assistant is told to ask you how sure you are of your time, early, and to flag any answer that depends on it.
- Within about five minutes, nothing material changes. If your time turns out to be wrong, we rebuild the file free — support@astrodai.in.
Why another site shows something different
Almost always one of four things: a different ayanamsa, a different house system, true nodes instead of mean, or a different frame for the special points. Each is a defensible choice; what is not defensible is mixing them. Your file is one calculation with one set of settings from end to end, which is why its parts agree with each other.