Dwadasamsa D12 Chart

What this section adds

The calculator above gives you a table of D12 signs, the houses counted from the D12 Lagna, and a flag on any point that keeps its Rasi sign. This long section explains where the twelve-fold division comes from, what the classical texts say it is for, how the engine arrives at each row, how to read each kind of result, and where the chart stops being reliable. Every number quoted below was produced by running the same engine function the calculator calls; nothing here is an illustration made up for the page.

The classical rule, and where it is written

Brihat Parashara Hora Shastra opens its sixth chapter with a list of sixteen divisions of a sign, which it attributes to Brahma: Rasi, Hora, Dreshkan, Chaturthamsa, Saptamsa, Navamsa, Dashamsa, Dvadashamsa, Shodashamsa and seven finer ones (Ch. 6, Sl. 2-4). The Dvadashamsa is the eighth name on that list. Its rule takes one sloka. BPHS Ch. 6, Sl. 15 says the Dvadashamsa is one twelfth of a sign, 2.5 degrees each, and that its reckoning starts from the same sign. That is the entire instruction. There is no clause for odd and even signs, which sets it apart from the Saptamsa (D7) and the Dashamsa (D10), where the starting sign shifts for even signs, and no clause for movable, fixed and dual signs, which is what the Navamsa (D9) and the Shodashamsa (D16) depend on.

Saravali agrees. In its third chapter, immediately after describing the Vargottama Navamsas, Kalyana Varma states that the rulers of the Dwadasamsas start from that sign itself. Two classical authorities, one rule, no variant reading in either. That matters for a calculator: several vargas have competing constructions in different traditions, and a tool has to pick one. For D12 this corpus offers nothing to choose between.

The same BPHS sloka adds a second layer that the calculator does not show. Each of the twelve parts has a presiding name, and the four names Ganesh, Ashvini Kumar, Yama and Sarpa repeat three times across the sign. The text gives the list and stops; it does not say in that sloka how the names should change a reading, so this page reports the sequence and draws nothing further from it.

One consequence of the table is worth seeing early. The Drekkana (D3) rule in BPHS Ch. 6, Sl. 7-8 gives the three ten-degree thirds of a sign to the 1st, 5th and 9th signs from it. D12 parts 1, 5 and 9 open at exactly 0, 10 and 20 degrees and land on those same three signs. So the part that begins each Drekkana carries the Drekkana's own sign, and the three parts that follow it walk on through the next three signs. The engine encodes this directly: both charts start from the sign itself, D3 stepping four signs per part and D12 one.

What the texts read it for

BPHS Ch. 7, Sl. 1-8 assigns one subject to each division: the physique from the Lagna, wealth from the Hora, co-born from the Dreshkan, fortunes from the Chaturthamsa, sons and grandsons from the Saptamsa, the spouse from the Navamsa, power and position from the Dashamsa, and parents from the Dvadashamsa. That half-line is the whole classical basis for calling D12 the chart of parents. The chapter does not go on to give D12 rules for the mother or the father, and neither does any other passage in this corpus. The page above is therefore right to stop at placements.

Where BPHS does give rules about parents, it gives them for the Rasi chart, and it is not perfectly tidy about it. Ch. 9, Sl. 43-45 names the Sun as the indicator of the father and the Moon as the indicator of the mother. Ch. 11, Sl. 5 puts the mother among the matters of the fourth house, Bandhu Bhava. For the father the text points two ways: Ch. 11, Sl. 11 lists the father among the indications of the tenth house, Karm Bhava, while Ch. 20, on the ninth house, judges the father from the lord of Dharm Bhava (Sl. 3-6). Both statements stand in the same book. A careful reader keeps both in view rather than choosing the one that suits. The learn pages on the 4th house, the 9th house and the 10th house go through those chapters.

Put together, the classical picture is this. The parents are first a Rasi-chart question, read from the fourth, ninth and tenth houses, their lords, and the Sun and the Moon. The D12 is the division named as a second view of the same subject. In practice that means looking at where those same significators fall in D12: the D12 signs of the Sun and the Moon, and of the lords of the relevant Rasi houses. Pages such as Sun in the 9th house and Moon in the 4th house cover the Rasi side. Nothing in the sources lets a D12 layout be turned into a statement about a living person's mother or father, and this app does not attempt it.

How the engine computes it

The calculator calls one function, computeDwadasamsa, which is a single line: it hands the natal chart to the shared varga routine with twelve divisions and a start rule that returns the sign unchanged. Everything else happens in that shared routine, which also builds D3, D4, D7, D10 and the finer charts. The natal chart it receives is the same one the birth chart calculator draws: sidereal longitudes under the Lahiri ayanamsa, each stored as a sign and a degree within that sign.

1. 1.Collect ten points: the Ascendant and the nine grahas, Sun to Ketu.
2. 2.Set the arc of one part to 30 divided by 12, which is 2.5 degrees.
3. 3.For each point, divide its degree within the sign by 2.5 and drop the fraction. The result is 0 for the first part and 11 for the last; a guard caps it at 11 so a value of exactly 30 cannot overflow.
4. 4.Take the index of the sign the point occupies as the starting sign. For D12 the start rule adds nothing.
5. 5.Add the part number to the starting sign and wrap past Pisces back to Aries. That sign is the D12 sign.
6. 6.Mark the point as keeping its Rasi sign when the D12 sign and the Rasi sign are the same. The points so marked are also returned as one list.
7. 7.Take the D12 sign of the Ascendant as house 1 and list the remaining eleven signs in zodiac order as houses 2 to 12.
8. 8.Give each graha a house by counting whole signs from the D12 Lagna to the graha's D12 sign.

Three things follow from that procedure and are easy to miss. First, the engine places a point in a D12 sign, not at a D12 degree. Some software stretches each 2.5-degree part into a full 30 degrees and prints a degree for the varga; this engine does not, and no result on the page depends on one. Second, the houses are whole-sign houses, so two grahas in the same D12 sign always share a house. Third, because the count runs through twelve consecutive signs, each sign of the zodiac receives exactly one part from every sign: 144 parts in all, twelve landing on each sign. No sign is favoured by the arithmetic.

A worked example with real engine output

The sample on this page is a birth on 14 August 1994 at 06:42 in Ahmedabad. The table below shows the working the page does not: the Rasi position the engine started from, the part it fell in, and the count that produced the D12 sign.

Take the Sun as a check you can do by hand. 27.26 divided by 2.5 is 10.9; dropping the fraction leaves 10, so the Sun is in the eleventh part. Counting eleven signs from Cancer, with Cancer as the first, runs Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, Pisces, Aries, Taurus. The D12 Lagna is Leo, and Taurus is the tenth sign from Leo, so the Sun sits in D12 house 10. Every row can be verified the same way, with nothing but the Rasi degree and a list of the twelve signs.

Three patterns in this chart show how D12 rearranges a Rasi chart. Saturn is at 16.50 degrees of Aquarius, in the seventh part, and the seventh part always lands on the opposite sign; any point between 15°00' and 17°30' of its sign moves to the sign facing it. The Moon and Jupiter are both in Libra in the Rasi chart, eleven degrees apart; D12 sends them to Cancer and Pisces, four signs from each other. And the Moon and Mars, which sit in Libra and Gemini in the Rasi chart, meet in Cancer. A conjunction in the Rasi chart survives into D12 only when the two grahas are in the same 2.5-degree part, and a D12 conjunction says nothing about closeness in the sky.

How to read each kind of result

A D12 sign

The most direct reading of a D12 sign is as a dignity question: is the graha in a sign where it is strong, comfortable or uneasy? BPHS Ch. 6, Sl. 42-53 counts a division as a good one when it falls in the graha's exaltation sign, Mooltrikon sign or own sign, and adds that the divisions of a combust, defeated or weak graha should not be counted as auspicious. In the sample the Moon lands in Cancer, Mercury in Gemini and Jupiter in Pisces, each its own sign, while Mars lands in Cancer, the sign of its debilitation. Saravali Ch. 5, Sl. 31-33 has a one-line effect for the first case: a planet in its own Dwadasamsa makes a person devout and helpful. Saravali also says, at Ch. 51, Sl. 110, that the effects it describes for individual signs apply to the Dwadasamsas of each sign as well, which is the classical licence for reading a D12 sign with the ordinary meaning of that sign.

A D12 house

A D12 house number is a count of whole signs from the D12 Lagna, nothing more. The sources in this corpus give no table of graha-in-house results for the Dvadashamsa, so a house number here is best treated as structure: which grahas sit in angles from the D12 Lagna, which share a sign, which fall in the sixth, eighth or twelfth. The sample has Saturn and Rahu in house 1 with the Lagna, Venus and Ketu opposite in house 7, and the Moon and Mars together in house 12. Those are facts about the layout. Carrying the house meanings of the Rasi chart across unchanged is a modern habit, not something BPHS Ch. 7 states.

The flag for keeping the Rasi sign

The engine flags a point whose D12 sign equals its Rasi sign and names the flag vargottama, the term it also uses in D9. In D12 this can only happen in the first 2°30' of a sign, and it happens there in every sign. Compare the Navamsa, where Saravali Ch. 3 places the Vargottama part first in a movable sign, fifth in a fixed sign and ninth in a dual sign. Saravali attaches its praise to the Vargottama Navamsa of the Lagna specifically; it makes no matching statement about D12. So the flag on this page is an accurate description of the arithmetic, and should be read as that. In the sample only the Ascendant, at 2.33 degrees of Leo, is flagged.

Position inside the part

BPHS Ch. 7, Sl. 13-16 says a Hora gives full, medium and nil effects at its beginning, middle and end, and that the same applies to the Dreshkan, Chaturthamsa, Navamsa and so on. The engine does not grade this, but you can from the Rasi degree. The sample Ascendant at 2.33 degrees is 0.17 of a degree from the end of its part; Mars at 4.42 degrees of Gemini is near the end of the second part. By that sloka both would be read as weak expressions of their D12 sign, and both are also the points most likely to change sign under a small correction.

D12 inside the strength systems

The Dvadashamsa carries more weight in classical strength arithmetic than its half-line in Ch. 7 suggests. BPHS groups the divisions into four schemes and scores each out of twenty points, the Vimshopak Bal. In the six-division scheme, Shad Varg, the divisions are Rasi, Hora, Dreshkan, Navamsa, Dvadashamsa and Trimshamsa with figures of 6, 2, 4, 5, 2 and 1 (Ch. 7, Sl. 17-19). D12 is one of only six charts there, and worth as much as the Hora. Adding the Saptamsa gives the seven-division scheme, with the figures 5, 2, 3, 2.5, 4.5, 2 and 1. In the ten-division scheme every chart except the Rasi and the Shashtiamsa gets 1.5 (Sl. 20), and in the full sixteen-division scheme D12 is one of the nine divisions that get half a point each (Sl. 21-25).

The same seven divisions return in Shad Bala. BPHS Ch. 27, Sl. 2-4 defines Sapt Vargaj Bal as the strength a graha earns from its dignity in the Rasi, Hora, Dreshkan, Saptamsa, Navamsa, Dvadashamsa and Trimshamsa, on a scale running from 45 Virupas in a Mooltrikon sign down to 2 in the most hostile one. So a graha's D12 sign is one seventh of that component of positional strength. The Shad Bala calculator explains what this app computes there.

This app's Vimshopaka Bala calculator uses the sixteen-division scheme, so D12 carries 0.5 of the 20 points. For each of the seven grahas the engine takes the D12 sign, finds its dignity there, and awards a share of the half point: all of it for exaltation, three quarters for an own sign, five eighths for a friendly sign, half for a neutral sign and none for an enemy sign or debilitation. Mooltrikon is a degree range inside a sign, and a varga gives a sign without a degree, so outside the Rasi chart the engine tests it at degree zero: a graha whose range starts at 0 (the Sun in Leo, Mars in Aries, Jupiter in Sagittarius, Saturn in Aquarius) is labelled Mooltrikon and earns the full share. Rahu and Ketu are not scored at all.

The table makes the proportion plain. Jupiter is in its own sign in D12 and still has the lowest total of the seven, because half a point cannot outweigh the Rasi chart at 3.5, the Navamsa at 3 and the Shashtiamsa at 4. A strong D12 placement is one small entry in a ledger of sixteen. It is real, and it is small.

Other places the Dwadasamsa appears in the texts

Parents and strength are the two uses most people meet. The corpus holds several more, and they show how freely the classical authors used the twelfth part as a fine-grained position marker.

• A dasha condition. BPHS Ch. 46, Sl. 29-30 calls the Panchottari dasha suitable for those whose Lagna is in Cancer and also in the Cancer Dvadashamsa. Under the same-sign rule that means the first 2°30' of Cancer rising. The engine tests exactly this: the alternate dashas calculator computes the D12 Lagna and reports whether Panchottari applies to your chart, with the Ascendant and its Dwadasamsa stated as the reason.
• A condition on the Moon. Saravali Ch. 11, Sl. 9-10, in its chapter on what offsets difficulties shown at birth, says that the full Moon in a benefic's Dwadasamsa removes such indications. The text presents it as one mitigating factor among many; this app does not compute it.
• A multiplier for planetary rays. Saravali Ch. 36, Sl. 7-9 adjusts a planet's rays by its Dwadasamsa: doubled in a friend's, trebled in its own, reduced in an enemy's. The engine's planetary-rays calculation states in its own comments that it does not apply these rectifications, so the rays this app reports are the unrectified figure.
• Pre-natal and non-human charts. Saravali uses the Moon's Dwadasamsa in its conception chapter, and Ch. 55, Sl. 30-37 uses the Dwadasamsas of the Sun, Moon and Ascendant throughout its chapter on births other than human. These have no bearing on a personal reading and are named only to show the range.
• A lost birth year. BPHS Ch. 78, Sl. 5-6, on reconstructing an unknown horoscope from a question chart, takes the sign of the Dwadasamsa in which the Prasna Lagna falls as the sign Jupiter occupied at birth. This app's Prashna calculator does not perform that reconstruction.

What these have in common is that none of them reads D12 as a separate chart with its own houses. They use the Dwadasamsa of one point, the Lagna or the Moon or a single graha, as a refinement of where that point is. That is the older and better-attested use, and it is a good discipline for reading the table above: start with single placements before the whole wheel.

Birth-time sensitivity, measured

The existing page says a rounded birth time can change the D12 Lagna. Here is how fast, from five runs of the engine on the sample birth with only the clock time changed.

On that morning the Ascendant moved about 2.24 degrees every ten minutes, so a whole Dwadasamsa rose in roughly eleven minutes. The sample Ascendant at 2.33 degrees of Leo is 0.17 of a degree short of the boundary, which at that rate is under one minute of clock time. A birth recorded as 06:42 that happened at 06:43 would have a Virgo D12 Lagna, the Sun in house 9 instead of 10, and no flagged point at all. Hospital records are rarely kept to the minute, so this sample is a fair warning: its D12 houses should not be leaned on.

The speed of the Ascendant varies with the sign rising and the latitude, so eleven minutes is a figure for this chart, not a constant. The Lagna calculator shows your Ascendant degree; divide it by 2.5 and look at the remainder to see how close you sit to an edge.

The grahas are far steadier. In the hour between 06:12 and 07:12 the Moon moved from 24.35 to 24.93 degrees of Libra, about 0.58 of a degree, so it takes a little over four hours to cross one part. The Sun moved 0.04 of a degree in the same hour and spends about two and a half days in each. Saturn and the nodes did not shift at two decimals. So the sign column of a D12 table is usually robust even when the birth time is known only to the hour, with the Moon the first to change. The house column is a different matter and deserves trust only when the time is recorded to within a few minutes.

Limits, stated plainly

• Positions are computed from built-in formulas, not from the Swiss Ephemeris, as the methodology page sets out. A point within a few hundredths of a degree of a 2.5-degree edge may land in the neighbouring part in other software.
• Degrees are rounded to two decimals before the division. The rounding is far smaller than a part, yet it is one more reason to treat edge cases as undecided.
• A different ayanamsa moves every longitude by the same amount, which moves every point relative to the part boundaries. A D12 table made under another ayanamsa can differ in several rows without either being miscalculated.
• Rahu is the mean node. A true-node calculation can differ enough from it to change the nodes' D12 signs.
• The engine returns signs, houses and the same-sign flag. It does not return a D12 degree, aspects within D12, the presiding names, or any interpretation.
• The classical basis for the chart's subject is a single phrase in BPHS Ch. 7. Detailed D12 rules about parents found elsewhere are later practice, which this page neither reproduces nor endorses.

Where it connects

Within a signed-in chart, the Kundali feature draws D12 as a chart wheel beside the Navamsa, Saptamsa and Dashamsa, from the same function this calculator calls, so the two will always agree. BPHS Ch. 7 pairs D12 with its neighbours by subject: the Chaturthamsa (D4) for fortunes, the Saptamsa for children, the Navamsa for the spouse, the Dashamsa for position. Reading them side by side shows how one birth moment is cut at different widths. The article on the Navamsa as the second chart explains the general idea of a divisional chart, and the sources page lists the editions the engine cites.

Questions people ask about the Dwadasamsa

Is the Dwadasamsa the same as the twelve houses?

No. The twelve houses divide the sky around you at birth into twelve signs counted from the Ascendant. The Dwadasamsa divides each single sign into twelve parts of 2.5 degrees and assigns each part a sign. The number twelve appears in both, and the D12 chart then has its own twelve houses counted from its own Lagna, but they are separate constructions.

Does D12 tell me about my mother and father?

BPHS Ch. 7, Sl. 1-8 names parents as the subject read from the Dvadashamsa, and that is all it says. The sources behind this app give no D12 rules that produce statements about a parent, so the calculator reports placements only. The classical rules about parents that do exist are written for the Rasi chart: the Sun and the Moon as indicators, and the fourth, ninth and tenth houses.

Which is the father's house, the ninth or the tenth?

BPHS says both in different chapters. Ch. 11, Sl. 11 lists the father under the tenth house, and Ch. 20 judges the father from the lord of the ninth. This page reports the disagreement and does not settle it; a reading that uses the father's house should say which convention it follows.

Why do my grahas have D12 signs but the page says the chart is unavailable?

This calculator is registered as needing an Ascendant, because the D12 Lagna and every house number come from it. Without a birth time and a resolved place it returns an unavailable result and names what is missing. The Vimshopaka Bala calculator uses each graha's D12 sign without houses, and so works without a birth time.

Another site shows degrees in my D12 chart. Why does this one not?

Some software expands each 2.5-degree part to a full 30 degrees and prints the result as a degree in the varga. BPHS Ch. 6, Sl. 15 defines only which sign each part belongs to. This engine follows the sloka and returns a sign, so there is no D12 degree to show.

My D12 Lagna differs between two apps. Which is right?

Check your Ascendant degree first. If it sits within a fraction of a degree of a multiple of 2.5, a small difference in ayanamsa, in the planetary formulas or in how the birth time was entered is enough to move it across the edge. In the sample chart, one minute of clock time changes the D12 Lagna from Leo to Virgo. In that situation neither app is wrong; the birth time is simply not precise enough to decide.

Is a graha that keeps its sign in D12 especially strong?

The engine flags it, and the flag is accurate: the point is in the first 2°30' of its sign. Saravali Ch. 3 praises the Vargottama Navamsa of the Lagna and says nothing comparable about D12. What can be said from the sources is narrower: such a graha has the same dignity in D12 as in the Rasi chart, so in the Vimshopaka score it earns the same share in both.

How much does D12 count in a graha's overall strength?

It depends on the scheme. BPHS Ch. 7 gives it 2 of 20 points when six or seven divisions are used, 1.5 when ten are used and 0.5 when all sixteen are used. This app uses the sixteen-division scheme, so D12 can add at most half a point to a graha's total of 20. It is also one of the seven divisions in the Sapt Vargaj Bal component of Shad Bala (Ch. 27, Sl. 2-4).

Can I use D12 for timing events?

Not with anything this app computes. The only timing use of the Dwadasamsa in the engine is the eligibility test for the Panchottari dasha, which BPHS Ch. 46, Sl. 29-30 ties to a Cancer Lagna in the Cancer Dwadasamsa. Periods themselves are dated from the Moon's nakshatra, as the Vimshottari dasha calculator shows.