Moon sign (rashi) calculator

In jyotisha, your sign is the Moon

Almost everybody arrives here already holding a sign. It came from a newspaper column or an app, it is based on your birthday, and it is your tropical Sun sign. Jyotisha means something different by "your sign": it means the sidereal Moon sign, the rashi the Moon occupied at the moment you were born.

Two differences at once, and they compound. Different body — Moon rather than Sun. Different zodiac — sidereal rather than tropical. Which is why the answer this page gives you very often looks nothing like the one you grew up with, and why that is not a mistake by either side.

The two zodiacs, in one paragraph

Both systems divide the sky into twelve equal 30° segments. They disagree only about where segment one begins.

The tropical zodiac starts at the spring equinox — the point where the Sun crosses the celestial equator each March. That point is defined by the Earth's tilt, and the tilt precesses: the equinox drifts slowly backwards against the stars, one full circle every twenty-six thousand years.

The sidereal zodiac starts from a fixed point among the stars, so it does not drift. Two thousand years ago the two systems agreed. They have separated by about a degree every seventy-two years since, and today the gap is roughly twenty-four degrees. That gap has a name: the ayanamsa.

Twenty-four degrees is most of a sign. That is the entire reason a great many people are one sign in a horoscope column and the previous sign in a jyotisha chart — and it is arithmetic, not disagreement about the sky.

This page prints your sidereal Moon sign, your sidereal Sun sign, and your tropical Sun sign side by side, with the exact ayanamsa used. You should not have to take our word for which one you are; you should be able to see all three and where the gap comes from.

Which ayanamsa, and why it is not a free choice

There are several ayanamsa schemes — Lahiri, Raman, Krishnamurti, Fagan-Bradley and others — and they differ from each other by up to about two degrees. Two degrees will not usually move a sign, but it will move a nakshatra pada, and pada is what a naming ceremony depends on.

We use Lahiri, which is the ayanamsa adopted by the Indian Calendar Reform Committee and the one the overwhelming majority of Indian practice uses. We say which one on every answer, because a sidereal position quoted without its ayanamsa is an incomplete statement — and quoting one without it is how two correct calculations end up looking like a contradiction.

Why the Moon and not the Sun

The Sun moves about one degree a day, so a Sun sign is stable across a month and can be worked out from a birthday alone. That is convenient, and convenience is most of why western popular astrology settled on it.

The Moon moves about thirteen degrees a day and changes sign roughly every two and a half days. It cannot be guessed from a birthday; it has to be computed. Jyotisha uses it anyway, and the reason given is that the Moon is manas — the mind — and that most of what a chart is asked about concerns how a person experiences things rather than the fixed facts of their nature.

It has a practical consequence too. Because the Moon changes sign every two and a half days, a chart's Moon sign is far more diagnostic than its Sun sign — one twelfth of people born in a given season share a Sun sign, but the Moon sign cuts across that entirely.

Does the birth time matter here

Less than for the ascendant, more than for the Sun sign.

The Moon spends about two and a half days in a sign, so most of the time a birth time out by several hours will not move your rashi at all. But if the birth happened close to a sign change, it will — and this page tells you, by printing the window during which the Moon occupies that sign and flagging it when your birth sits near an edge.

If you do not know your birth time at all, run it with a noon estimate and read the window. If noon sits comfortably inside it, your rashi is safe regardless. If it sits near an edge, you have learned that your Moon sign genuinely depends on a fact you do not have — which is worth knowing before anyone builds a reading on it.

What we deliberately do not tell you

We do not give you a paragraph about what Taureans are like.

There is a large body of sign-personality writing and very little of it is in the texts this engine cites. More to the point, a Moon sign is one factor among many — the ascendant, the lord's placement, the running dasha, the aspects — and a reading built on the sign alone is not a reading of a chart. Handing one over would make this page feel more satisfying and be worth less.

We also do not tell you which zodiac is correct. They measure from different starting points, both are internally consistent, and the argument is older than either of us.

Common questions

So which sign am I really?

Both, in different systems. If someone is doing jyotisha with you, they mean your sidereal Moon sign. If you are reading a horoscope column, it means your tropical Sun sign. The answer above gives you all three so the question stops being confusing.

Why does the ayanamsa keep changing?

Because precession is continuous. The ayanamsa grows by about fifty seconds of arc a year, so the figure printed for a 1975 birth is genuinely different from the one printed for a 2005 birth. That is correct behaviour, not instability.

Is the Moon sign the same as the birth star?

No, though both come from the Moon. The rashi is one of twelve 30° divisions; the nakshatra is one of twenty-seven 13°20' divisions. A rashi contains a little over two nakshatras. Our nakshatra calculator gives you the other one.

Do you keep my birth details?

No. The details come in for the computation and are dropped when the answer goes back. No account, no email, nothing written anywhere — which is why there is no consent box on the form.