Our methodology

1 — Turn a clock reading into an instant

“Half past six in the morning, Calcutta, June 1943” is a reading off a clock. It is not a moment in time, and the grahas can only be placed at a moment. So the first thing we work out is the UTC offset that was legally in force at that place on that date, and subtract it. For a 1943 Indian birth that offset is not today’s +05:30 — see the table below. Every step after this one assumes this step was right, which is why it goes first and why the rest of this page keeps returning to it.

2 — Compute the positions, rather than look them up

The grahas are computed for that exact instant by our own calculation engine, from the astronomy, at the second. They are not interpolated from a printed almanac that gives one row per day, and they are not written by a language model. The Sun, Moon, Mars, Mercury, Jupiter, Venus and Saturn are computed directly; Rahu is the Moon’s node and Ketu is Rahu plus exactly 180°, because the two nodes are a geometric pair and not two independent bodies.

3 — Convert tropical to sidereal, with the Lahiri ayanamsa

Positions come out of the astronomy measured from the equinox, which drifts. Jyotisha measures from the fixed stars, so we subtract the ayanamsa — the angle between the two zodiacs, currently about 24°. We use Lahiri (Chitrapaksha), the value the Calendar Reform Committee settled on in 1955 and the one the Rashtriya Panchang has been published from ever since. It is the Indian civil standard, which is why the tithi on this site agrees with the panchang on your wall. Skip this step and almost every graha lands in the neighbouring rashi; use a different ayanamsa and a birth near a sign boundary changes sign.

4 — Whole-sign houses: one rashi is one house

The rashi the lagna falls in is the entire first house, the next rashi is the second, and so on around the wheel. There are no cusps to interpolate and no house that straddles two signs. This is what the Parashari texts assume, and it is what makes a chart here comparable with one drawn by a pandit from the same tradition. The quadrant systems (Placidus, Koch and the rest) belong to a different chart form built for a different latitude range; running one silently reassigns planets to houses they are not in.

5 — Derive everything else from those same numbers

Your janma nakshatra and pada come from the Moon’s sidereal longitude. The Vimshottari dasha balance you are born with comes from how far throughthat nakshatra the Moon had travelled. Tithi comes from the Moon’s elongation from the Sun, yoga from their sum, gun milan from the two Moons. One set of positions feeds every reading on the site, so the dasha, the matching score and the panchang can never quietly disagree about where your Moon was.

A birth time is meaningless without the offset that was in force when it was read. India changed that offset five times, and the popular version of the story — “wartime time, 1942 to 1945” — is wrong at both ends. This is what the clocks really said, and it is what we resolve against, transition by transition:

Until 1854+05:53:28

Calcutta local mean time — the Sun over that meridian, to the second. Not a round number, and we do not round it.

1854 – 1870+05:53:20

Howrah Mean Time.

1870 – 1906+05:21:10

Madras Mean Time. A birth in this window resolved at the modern +05:30 is nine minutes out — small, and still enough to change the rashi of a lagna sitting near a boundary.

1906 – 1 Oct 1941+05:30

Indian Standard Time is adopted. For thirty-five years the modern offset is also the correct one.

1 Oct 1941 – 15 May 1942+06:30

Clocks are advanced an hour for the war. The advance opens here, in late 1941 — a year earlier than the story everyone tells.

15 May – 1 Sep 1942+05:30

A four-month hole in the middle of the wartime period, back on standard time. Anyone bracketing on “1942–45” gets these births wrong in the opposite direction to all the others.

1 Sep 1942 – 15 Oct 1945+06:30

The advance resumes and runs to the end of the war.

Since 15 Oct 1945+05:30

IST, unbroken — and the offset most astrology software applies to every Indian birth ever recorded, including the ones above.

The place matters as much as the date: we resolve the zone from the coordinates of the birthplace you pick, not from the country. A birth in Kathmandu or Karachi gets its own history, not India’s.

The lagna is simply which part of the zodiac was rising in the east at your birth, and the sky turns a full circle in a day — about 15° an hour, or one degree every four minutes. So an error in the time is an error in the lagna, and the lagna decides which house every graha lands in:

Out by 4 minutes

About one degree of lagna. Below the noise in almost any recorded birth time, and it changes nothing you would notice.

Out by 30 minutes

About seven and a half degrees — a quarter of a rashi. Harmless in the middle of a sign, decisive within 8° of its edge.

Out by 1 hour

Fifteen degrees: half a rashi. This is exactly what an unhandled wartime clock does to a 1943 birth, and it is why that table is above this one.

Out by 2 hours

A whole rashi, near enough. The lagna is a different sign, so every graha sits in a different house and the entire reading is a different reading.

Out by The date only

Nothing that depends on the lagna survives, so no house placement can be trusted. The Moon spends about two and a quarter days in a rashi, so the moon sign usually does survive — its nakshatra will not.

The Moon is slower and therefore more forgiving — it covers about half a degree an hour, crossing one nakshatra a day and one pada roughly every six hours. But your Vimshottari dasha balance is read off exactly how far through that nakshatra the Moon had got, so an hour of uncertainty in the birth time can move the start of a dasha by months. If you know your time only to the nearest hour, treat the dasha dates as approximate and the house placements as provisional.

Bombay Time, which no database records

Bombay ran about 39 minutes behind IST on its own local time until 1955. It was real, it was widely used, and it is not encoded in the time-zone data anywhere — all of India is modelled as one zone from 1906. So a pre-1955 Bombay birth carries roughly 39 minutes of genuine uncertainty, about 10° of lagna, depending on which clock the time was read from. We cannot resolve that for you. We would rather print it here than let you find out later.

Clock readings that happened twice, or never

When India came off wartime time on 15 October 1945 the clocks went back an hour, so every wall-clock reading in that hour genuinely occurred twice — and the two instants give two different charts. On 1 September 1942 an hour was skipped and never occurred at all. Most software silently picks one and reports no doubt. We detect both cases and treat them as a question for you, because a coin flip dressed as a chart is worse than an admitted gap.

The birth time you were given

Indian birth records round, usually to five minutes and often to the quarter hour, and a time recalled by a relative is rounded harder than that. We compute exactly the moment you enter. We have no way of computing what the clock in the room actually read, so the row you should read in the table above is the one matching how sure you are — not the one matching how precise the field looks.

Interpretation is not calculation

Everything above is arithmetic: it is either right or wrong, and it can be checked. What a placement means is a reading, and different schools of jyotisha read the same chart differently — legitimately. Where a convention had to be chosen we say which one we follow. We do not claim it is the only one, and nothing on this site predicts what will happen; see the disclaimer for what these readings are and are not.

The engine is held to a fixed set of reference charts that it has to reproduce before any change to it can ship. They assert the things a reader would notice — this lagna, this nakshatra, this pada — rather than raw longitudes, so a genuine refinement of the astronomy passes and a sign that quietly flips fails loudly. Several of those reference births are deliberately wartime and pre-1906 Indian ones, because those are exactly the charts an offset bug moves while still looking entirely plausible.

Each saved chart also records the version of the engine that produced it, so a chart stored last year can never be served as though the maths behind it had not changed.

That is the whole method. Make your kundli and every number on it will have come from the steps above — or write to us at contact if one of them does not look right to you.