Both biodatas show the same birth star

The biodatas have been exchanged, and someone notices it: both say the same nakshatra. Or both say the same rashi. The question comes at once. Is a marriage in the same birth star allowed?

Two words carry the whole question. The rashi is the Moon sign, the one of the 12 signs the Moon was in at birth. The nakshatra is the birth star, the one of 27 star groups the Moon was in. Each nakshatra spans 13°20′ of the sky and is split into four padas (quarters) of 3°20′ each. A marriage biodata usually prints all three lines: rashi, nakshatra and pada. Our biodata guide shows where each one is written.

Because a sign is 30° and a star is 13°20′, each sign holds two and a quarter stars. So nine of the 27 stars cross from one sign into the next: Krittika, Mrigashira, Punarvasu, Uttara Phalguni, Chitra, Vishakha, Uttara Ashadha, Dhanishta and Purva Bhadrapada. Two people born in one of these nine stars can share the star and still have different Moon signs.

That gives four cases, and they score very differently. The same star in the same pada. The same star in a different pada, in the same sign. The same star in two different signs. And the same sign with two different stars. This guide works out each one with our matching engine, for every star and every pada, with the Moon placed at the middle of each pada, so you can find yours.

What a shared star does to the eight kootas

The usual North Indian method, Ashtakoot ("eight parts"), compares two charts in eight tests called kootas and gives 36 points in all. Every one of the eight reads only two facts from each chart: the Moon sign and the birth star with its pada. Four kootas read the Moon signs: Varna (1 point, the class of each sign), Vashya (2, whether one sign draws the other), Graha Maitri (5, whether the planets that rule the two signs are friends) and Bhakoot (7, how many signs apart the two Moons sit). Four read the birth stars: Tara (3, the count from one star to the other), Yoni (4, the animal each star is paired with), Gana (6, the temperament group of each star) and Nadi (8). Our 36-gunas guide explains each one.

Now give both people the same star. Seven of the eight kootas reward sameness. The same star gives the same Yoni animal (4 of 4) and the same Gana temperament (6 of 6). Tara counts from one star to the other, and the same star counts as the first, which our tables score 3 of 3. If the two Moon signs are also the same, Varna, Graha Maitri and Bhakoot score full too, because each compares a sign with itself, and so does Vashya, except in the two signs it splits in half (more on that below).

Nadi (nāḍī, "channel") works the other way. It puts every star in one of three groups of nine, and it scores 8 points only when the two stars sit in different groups. The same star is always the same group. So a shared star always starts at Nadi 0 of 8, and the only question is whether one of the exceptions gives the 8 points back. That is what the pada and the sign decide.

The same star, the same pada: 28 of 36, with a zero inside

When both biodatas show the same nakshatra and the same pada, the two Moons sit within the same 3°20′ of sky, in the same sign. Our engine scored this case for all 108 padas. For 106 of them the result is the same: 28 of 36, with seven kootas full and Nadi at 0 of 8. The other two are Purva Ashadha pada 1 and Shravana pada 2. Each sits across a 15° line that Vashya uses, so two Moons on opposite sides of it lose 1 Vashya point, and our kundli milan page shows 27 to 28 for them.

Read that number carefully. A total of 27 or more is what our kundli milan page calls a strong total, and 28 is above that line. Yet the whole gap is one koota at zero, and it is the heaviest of the eight. This is the clearest case of a total hiding its parts. A family that looks only at "28 gunas" sees a good match; a family that reads the eight lines sees a Nadi dosha (dosha, "fault").

None of the three exceptions our matching tests applies here, because each one needs something to differ: the star, the sign or the pada. So our matching leaves this Nadi at 0 of 8. Some sources go further and exempt the same star in the same pada for a list of particular stars. Those lists differ from source to source, so our matching does not apply that rule, and we name no list here. If your family follows such a list, it is following its own source, which it is free to do.

The same star, a different pada: the Nadi points come back

Now say both biodatas show the same star but different padas, and the same Moon sign. This is the most common shared-star case: our engine finds 264 such pairings of star and pada. Here a widely followed exception applies: the same star in different padas gives the 8 Nadi points back. The usual reason given is that the padas fall in different navamsha signs (the ninth-part signs a chart is divided into), so the two Moons are not in the same place.

With Nadi restored, almost nothing else is lost. Of the 264 pairings, with the Moon at the middle of each pada, 258 score the full 36 of 36. The other six score 35, all in Shravana when its first pada is paired with a later one, because Vashya splits Makara (Capricorn) in two at 15°. For the two padas that sit across such a line, Shravana pada 2 and Purva Ashadha pada 1, the kundli milan page shows a small range.

So the same star with a different pada is, on the 36-point count, close to the best result there is. The exceptions are a convention, though, not a rule we can cite to a text and verse. Our Nadi Dosha check says so on the page, and it names which exception decided your pair.

One star across two signs: Nadi comes back, Bhakoot may go

The nine stars that cross a sign boundary give a third case: the same star, but the two Moons on either side of the line, in two different signs. The second exception applies, the same star in different Moon signs, and the 8 Nadi points come back.

But a different sign changes the four sign kootas. The two signs are neighbours, and neighbouring signs sit 2 and 12 apart, one of the three distances that score Bhakoot 0 of 7. Our matching gives the 7 points back only when the planets that rule the two signs are the same planet or natural friends of each other. For three of the nine stars they are, and for six they are not.

The list below gives what our engine finds for each of the nine stars, across every pair of padas that falls in two signs. The first three keep Bhakoot. In the last six, Bhakoot is 0 and Graha Maitri drops too.

So a shared star across a sign boundary trades one zero for another. For six of these stars the Nadi zero is gone, but a Bhakoot zero takes its place, and the total lands between 22½ and 27. Our Nadi and Bhakoot guide explains how much weight a Bhakoot zero carries.

• Mrigashira, across Vrishabha (Taurus) and Mithuna (Gemini): 34 to 35 of 36. Bhakoot kept, because Venus and Mercury are friends.
• Chitra, across Kanya (Virgo) and Tula (Libra): 35 to 36. Bhakoot kept, for the same reason.
• Dhanishta, across Makara (Capricorn) and Kumbha (Aquarius): 33½ to 34½. Bhakoot kept, because Saturn rules both signs.
• Krittika, across Mesha (Aries) and Vrishabha (Taurus): 26 to 27. Bhakoot 0.
• Uttara Ashadha, across Dhanu (Sagittarius) and Makara (Capricorn): 26 to 27. Bhakoot 0.
• Uttara Phalguni, across Simha (Leo) and Kanya (Virgo): 25 to 26. Bhakoot 0.
• Vishakha, across Tula (Libra) and Vrishchika (Scorpio): 25 to 26. Bhakoot 0.
• Purva Bhadrapada, across Kumbha (Aquarius) and Meena (Pisces): 24½ to 25½. Bhakoot 0.
• Punarvasu, across Mithuna (Gemini) and Karka (Cancer): 22½ to 23½. Bhakoot 0.

The same rashi, a different star

The fourth case is the one families ask about as "same rashi marriage": the same Moon sign, but two different stars. Our engine finds 600 such pairings of star and pada.

In every one of them, Nadi scores 8 of 8 and Bhakoot scores 7 of 7. Bhakoot is full because the two Moons are in one sign. Nadi is full for one of two reasons. Most pairs have two stars in different Nadi groups. In 144 pairs the two stars share a Nadi group, and the first exception gives the 8 points back: the same Moon sign with different stars. Together those two kootas carry 15 of the 36 points, so a shared rashi never loses them in our matching.

The totals run from 24½ to 36. Where points go, they go mostly on the star kootas: Yoni (the two animals) and Gana (the two temperaments) most often, and Tara sometimes. Vashya, a sign koota, loses points only in Dhanu and Makara, the two signs it splits in half. Our guides to Gana koota and Yoni koota show those tables.

Where custom, not the score, decides

Everything above is arithmetic from our tables. Custom is a separate question, and families answer it differently. Some families decline a match in the same birth star whatever the score says. Some accept it when the padas differ. Some follow a list of stars for which they accept even the same pada. Some never look at the star at all. None of these positions is the only Hindu one, and this guide does not tell you which to follow.

Regional practice differs as well. In much of South India, families read a set of ten tests called the poruthams instead of a 36-point total, and those tests read two stars by their own rules. Our guide to Dasa Porutham and the 36 gunas compares the two systems test by test. Different calculators also apply different exceptions, which is one reason two sites can give the same pair two totals; our guide to why matching sites give different scores goes through every cause.

Whatever the custom, a shared star or a shared sign is one comparison of two Moon positions. It reads nothing else in either chart, and it does not say what will happen in a marriage. Families who take it seriously usually take both full charts to an astrologer they trust.

Check your own two stars

You can work out your case in a minute. Our Nadi Dosha check takes the two birth stars and padas, needs no birth time and no account, and names which exception, if any, decided the Nadi. Our kundli milan page has a block called "Rebuild it from the two birth stars", below the box for a total score. It rebuilds all eight koota scores from the same two stars and padas, shows the total and its tier, and saves nothing you type. It asks which star is the boy’s and which is the girl’s, because two kootas read from one side to the other.

If a biodata does not print the pada, our signs page finds the Moon sign, the birth star and its pada from one birth date, time and place, and saves nothing. The pada changes about every six hours, so it rests on the birth time.

Practical takeaway: read the three lines on both biodatas, rashi, nakshatra and pada, and find your case. The same star in the same pada is about 28 of 36 with a Nadi zero, whatever the total suggests. A different pada brings the Nadi points back. A star across two signs brings them back but may cost Bhakoot. The same sign with different stars keeps both. Then decide the custom question as a family, separately from the arithmetic.

• The same star in the same pada: 28 of 36 (27 to 28 in two padas), with Nadi 0; our matching applies no exception.
• The same star in a different pada, same sign: 35 or 36 of 36, Nadi restored by an exception.
• The same star in two signs: Nadi restored; six of the nine border stars lose Bhakoot, totals 22½ to 27.
• The same sign with different stars: Nadi and Bhakoot always full in our matching; totals 24½ to 36.