How Nyovah Calculates Your Chart

Everything below describes what our calculation engine does today, not what we intend it to do. Where there is a limit, it is stated next to the method.

The Short Version

Where the Planet Positions Come From

The Sun and Moon are computed with the methods in Jean Meeus's Astronomical Algorithms (2nd edition), including his full 60-term table for the Moon. Mercury through Saturn come from astronomy-engine, an open-source VSOP-based ephemeris, as apparent positions: corrected for the time light takes to reach us. Rahu is the mean lunar node, and Ketu is placed exactly opposite it.

These calculations give tropical positions, measured from the spring equinox. Vedic astrology measures from the stars instead, so one more step is needed: subtract the ayanamsa.

The Ayanamsa: Lahiri, and a Small Gap We Keep on Purpose

The ayanamsa is the distance between the two zodiacs. It grows slowly every year because the equinox drifts against the stars. Nyovah uses Lahiri (Chitrapaksha), the standard adopted by the Government of India, for every chart, the KP view included.

We compute it from one fixed formula: 23.8532° at the start of the year 2000, increasing by 50.291 arc-seconds a year. In October 2026 that comes to about 24.23°.

Lahiri is not implemented identically everywhere. Our value runs about 35 arc-seconds below Drik Panchang's, consistently. That is how far the Moon moves in about one minute, less than the rounding on almost any birth certificate. Here is what it does and does not change:

• Your birth chart: signs, houses and nakshatras come out the same unless a planet sits within a hair of a boundary.
• Transit dates: the moment a slow planet changes sign can land an hour or two earlier on our side. When that moment falls close to midnight, the calendar day can differ by one.
• Dasha dates: this is where it would show. Dasha dates are highly sensitive to the Moon's position. On a Venus mahadasha boundary, one arc-minute of Moon is roughly nine days. A 35 arc-second change would move a mahadasha boundary by about two to five days, depending on which nakshatra the Moon is in.

That last point is why we do not chase the gap. Part of it comes from our formula itself: it is a straight-line formula, which leaves out nutation, a small natural wobble of the Earth's axis. We use that simpler fixed formula and keep it frozen, because changing it now would silently move every saved chart's dasha dates by a few days. The date you were shown last month should be the date you see today. If you ask the reading to check a sky-change date against another panchang, it tells you about this gap.

House Systems: Whole Sign, and KP Kept Separate

The main chart uses whole-sign houses. The sign rising at birth is the 1st house in full, the next sign is the 2nd, and so on. A planet's house is simply the sign it occupies, counted from the rising sign. Yogas, dignities, the houses a dasha lord activates and the main reading all use this.

KP uses real Placidus cusps. Krishnamurti Paddhati is defined on Placidus houses, which are unequal and depend on the latitude and the exact moment of birth. Its key judgement, the sub-lord of a house cusp, needs the cusp's exact degree. Nyovah used to approximate KP cusps with equal houses from the rising degree; measured across 2,000 random Indian charts, that put the 10th cusp's sub-lord wrong about three times in four. So KP now gets true Placidus cusps, computed from your birth coordinates and moment.

Two consequences follow, and both are intended:

• A planet can sit in a different house in KP than in your main chart. KP counts a planet into the house whose cusp span contains it. A planet near a cusp can be in your 9th house by whole sign and your 10th by KP. We never mix the two: the main reading uses whole-sign houses, and the KP analysis uses its own.
• When Placidus cannot be computed, KP verdicts are withheld rather than guessed. Placidus has no valid answer inside the polar circles, and an old saved chart may lack birth coordinates. In those cases the KP event verdicts are not shown, and the reason is stated.

Birth Time Zones, Including India's War Time

The rising sign moves through a whole sign in about two hours, so an hour's error in the time zone can put your chart in the wrong rising sign. The time on a birth certificate is local clock time, and local clocks have not always run on today's offset.

When you choose your birth place, Nyovah finds its time zone from the coordinates, using an offline map of time zone boundaries rather than a third-party service, and then asks the standard time zone database what offset was in force at that place, on that date, at that hour. For Indian births that means:

A birth in a War Time window was recorded on clocks running an hour ahead. Cast at +05:30, that chart would be an hour off. Outside India the same lookup applies daylight saving and each country's own history. If the clock showed your birth time twice because clocks went back that night, we use the first occurrence and tell you; if the clock skipped that time, we ask you to check it.

The limit: the time zone database treats all of India as one zone from 1906. Some cities kept their own local time for years after that, and the database does not record it. If your birth record was written in a city's local time, use Change next to the detected time zone on the birth form and pick the offset yourself. The offset in use is always shown on the form.

How Dasha Dates Are Derived, and Locked

Vimshottari divides a 120-year cycle among nine planets in a fixed order: Ketu 7 years, Venus 20, Sun 6, Moon 10, Mars 7, Rahu 18, Jupiter 16, Saturn 19, Mercury 17. Your starting point comes from one number, the Moon's exact sidereal position at birth:

• The nakshatra the Moon occupies sets the first mahadasha: its lord rules first.
• How far the Moon has already travelled through that nakshatra, a span of 13°20′, sets how much of that first period was already used up before birth. What remains is the balance of dasha.
• Every later mahadasha follows in order, with a year counted as 365.25 days.
• Each antardasha lasts mahadasha years × antardasha years ÷ 120. Each pratyantara lasts the product of all three planets' years ÷ 14,400. Both start from their parent's lord and run in the same order.

Every boundary is shown as an exact calendar date. Never "around early 2027".

Because the whole timeline hangs off the Moon's position, small changes ripple far: one arc-minute of Moon moves a Venus mahadasha boundary by roughly nine days. That is why the inputs to this calculation are frozen. Seven dates on a fixed reference chart (two mahadasha boundaries, two antardasha boundaries and three pratyantara boundaries) are pinned in our test suite with zero tolerance. If a code change moves any of them by a single day, the tests fail.

The Rule: The Language Model Explains, It Never Calculates

Nyovah's written readings and answers are drafted by a language model. It is the part of the system that is good with words and unreliable with arithmetic, so it is kept away from the arithmetic entirely.

Everything factual is computed first, by code: planet positions, signs, houses, dignities, combustion, the yogas present in your chart with their classical sources, your full dasha timeline, and which transits are touching your chart today. The model receives that finished set of facts and is instructed:

• not to recalculate anything, and not to change any position it is given;
• not to mention a yoga that is not in the computed list, because if it is not listed, it is not in the chart;
• to quote the current antardasha's end date exactly as computed, never rounded or re-derived;
• to state only the future sky-change dates it has been given, and to say plainly when it does not have one, instead of supplying a date from memory.

Instructions alone are not trusted to hold. Before a chat answer reaches you, a check on our side looks for a dasha date the model has blurred, such as "late October 2026", and replaces it with the one exact date from the computed facts that it stands for. If no single computed date matches, it changes nothing rather than guess.

The practical effect: the facts in your reading are the same every time you ask. What can vary is the wording around them.

If You Don't Know Your Birth Time

You can still make a chart. Choose "I don't know my birth time" and the chart is cast for 12:00 noon, a placeholder, and labelled as time unknown wherever the time is shown.

Here is what that costs. Your Moon sign is usually still right, since the Moon spends about two and a half days in a sign. But the rising sign changes roughly every two hours, so the houses may be wrong, and the dasha dates can move by years across a single day. Even the period you are in right now can differ.

So we say so, instead of presenting noon as fact. In the chat, the first answer states once that the dates are estimates until the birth time is known, and the reading avoids claims that depend on the rising sign or houses. The Today summary marks each dasha date as an estimate, and the Timeline carries the same caveat. Adding your birth time later, through Edit details, recomputes everything.

What This Page Does Not Claim

Our engine is not Swiss Ephemeris, and we do not say it is. It is independently implemented and checked against published worked examples and against established panchangs. Jyotish has several valid conventions, and a different ayanamsa or house system will give different houses without either side being wrong. What we can promise is narrower: the method above is the one actually running, it is applied the same way to every chart, and when our number differs from someone else's, you can now see why.