Drekkana D3 Chart

What this page adds to the calculator above

The calculator above gives you the D3 sign of your Ascendant and nine grahas, a twelve-house layout and a list of points that keep their Rasi sign. The short notes beside it explain the arithmetic in two paragraphs. This longer section does the rest of the job: where the Drekkana comes from in the classical texts, the full table of all 36 divisions, a line-by-line walk through one real chart, how to read every value the calculator can return, what the old authors actually did with this chart, and - just as important - which of those uses this app does not attempt.

Everything below is drawn from two classical texts, Brihat Parashara Hora Shastra (BPHS) and Kalyana Varma's Saravali, and from the engine code that runs when you press the button. Chapter and sloka numbers are given so that each statement can be checked on the sources page. Where the two texts disagree, the disagreement is stated instead of smoothed over.

Where the Drekkana comes from

BPHS Ch. 6 lists sixteen ways of dividing a rashi and attributes the list to Brahma: Rasi, Hora, Dreshkan, Chaturthamsa, Saptamsa, Navamsa, Dashamsa, Dvadashamsa, Shodashamsa, Vimshamsa, Chaturvimshamsa, Saptavimshamsa, Trimshamsa, Khavedamsa, Akshavedamsa and Shashtiamsa (Sl. 2-4). The Drekkana is third in that list, immediately after the whole sign and the half sign. The spelling varies with the translator - Dreshkan and Drekkan in the BPHS translation used here, decanate and Drekkana in the Saravali translation - but they are one and the same division.

The rule itself occupies two slokas. BPHS Ch. 6 Sl. 7-8 says that one third of a rashi is called Dreshkan, that there are 36 of them in the zodiac, 'counted from Mesh, repeating thrice at the rate of 12 per round', and that 'the 1st, 5th and the 9th Rasis from a Rasi are its three Dreshkanas'. It then names three sages - Narada, Agasthya and Durvash - as presiding over the first, second and third part respectively. This calculator does not print those names; they are mentioned here because the text gives them and because they are sometimes confused with the planetary lords of the parts.

Saravali states the same rule in terms of lords. Ch. 3 Sl. 14 says the lords of the decanates are 'first Lord of the same Rasi, second Lord of the 5th Rasi therefrom and third Lord of the 9th from the Rasi in question'. So the two texts in this app's library agree on the counting: first part in the sign itself, second part in the fifth sign, third part in the ninth. Saravali Ch. 3 Sl. 17 adds a small piece of bookkeeping - 24 Horas and 36 decanates make 60 divisions between them - and Sl. 18 gives a general formula for any varga: convert the longitude to minutes of arc, multiply by the varga figure and divide by 1800, the number of minutes in a sign. For the Drekkana the varga figure is 3. We test that formula against the engine further down.

The word trine matters here. The fifth and ninth signs from any sign, together with the sign itself, form a closed group of three: count the same way from any member and you land on the other two. The twelve signs therefore fall into four such groups, and the Drekkana never leaves the group its Rasi sign belongs to. That is the structural difference from the Navamsa (D9), which walks through consecutive signs, and from the Hora (D2), which only ever resolves to the Sun's or the Moon's half.

All 36 Drekkanas in one table

Because the rule has no odd or even exception, the whole system fits in twelve rows. The sign columns are what this calculator returns. The lords in brackets follow Saravali Ch. 3 Sl. 14 - the lord of whichever sign the part falls in - and are shown for reference; the calculator's result does not carry a lord field.

Three things can be read straight off this table, and each explains something you will see in a result.

• Every sign appears exactly three times, once in each column. A given D3 sign can therefore be reached from three different Rasi signs. Gemini in D3 is the first third of Gemini, the second third of Aquarius and the last third of Libra.
• The first column repeats the Rasi sign. That is why a point in the first 10 degrees of its sign is always flagged as keeping its sign, and no point beyond 10 degrees ever is.
• A D3 sign is never next to its Rasi sign. It is the same sign, or four signs on, or eight signs on. If another program shows a D3 placement in a neighbouring sign for the same degree, it is using a different counting rule from the one BPHS and Saravali give.

How this calculator computes your D3 chart

The notes above the fold describe the division and the step of four. Here is the whole pipeline in order, from the form to the result, as the code runs it. The first two steps are shared with the Lagna calculator and the third onward belong to the divisional routine in the Kundali engine.

1. 1.Your birth date, time and place are read, the place is resolved to real coordinates, and the local time is converted with the IANA time zone of the place for that date. If any of the three is missing, nothing is computed (see the section on refusals below).
2. 2.A sidereal chart is built: the Ascendant and the nine grahas each get a sign and a degree within that sign. This is the Rasi chart, D1.
3. 3.For each of the ten points the engine takes the degree within the sign and divides by 10, the width of one part (30 divided by 3). The whole-number part of the answer is the index of the third: 0, 1 or 2.
4. 4.The index is capped at 2, so a degree that prints as 30.00 because of rounding is kept in the last part of its own sign and does not spill into a fourth part that does not exist.
5. 5.The count starts from the point's own Rasi sign. The start function for D3 simply returns the sign it was given; the code comment records that the source makes no odd or even distinction for this varga.
6. 6.The index is multiplied by four and added to the sign's position in the zodiac, wrapping after Pisces. Index 0 gives the sign itself, index 1 the fifth sign, index 2 the ninth.
7. 7.The point is flagged as keeping its sign when the D3 sign and the Rasi sign are the same.
8. 8.The D3 sign of the Ascendant becomes house 1, the next sign house 2 and so on. Each graha's house is the number of signs from the D3 Lagna to the graha's D3 sign, counting the Lagna's sign as one.

That is all of it. There is no separate table of 36 entries stored anywhere in the code; the table in the previous section is what the formula produces, not what it reads. The same routine, given 7, 9, 10 or 12 parts and a different start rule, produces the other divisional charts, which is why a correction to one of them is a correction to all.

A worked chart, point by point

The sample person on this page was born on 14 August 1994 at 06:42 in Ahmedabad. Running that birth through the engine gives the following Rasi positions and D3 placements. The numbers are the engine's own output, not rounded for presentation.

Following three of the rows by hand

Take the Sun at Cancer 27.26. Dividing 27.26 by 10 gives 2.726; the whole number is 2, so this is the third part. Two steps of four signs from Cancer is eight signs on: Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, Pisces. The Sun's D3 sign is Pisces, the ninth from Cancer, as the table of 36 says. Saravali's formula reaches the same part by a different road: 27.26 degrees is 1,635.6 minutes of arc; multiplied by 3 that is 4,906.8; divided by 1,800 it is 2.726 - two parts completed, the third in progress.

Take Jupiter at Libra 13.55. The division gives 1.355, so the index is 1, the second part. One step of four signs from Libra is Aquarius, the fifth from Libra. And take Mars at Gemini 4.42: the index is 0, no steps are taken, and Mars stays in Gemini. Mars is one of the two points flagged as keeping its sign; the other is the Ascendant at Leo 2.33, for the same reason.

Why four points share Gemini

The most striking feature of this result is the group in Gemini: the Moon, Mars, Saturn and Rahu. In the Rasi chart those four are spread over three different signs - Mars in Gemini, Saturn in Aquarius, the Moon and Rahu in Libra. They meet in D3 because Gemini, Libra and Aquarius are one trine group and the three thirds involved all point to the same member of it: the first third of Gemini, the second third of Aquarius and the last third of Libra. Jupiter is also in Libra, but in its second third, so it goes to Aquarius instead and does not join them.

This is the general pattern to expect. A gathering of grahas in one D3 sign is not evidence that they are together in the sky. It tells you that they occupy the same trine group in the Rasi chart at matching thirds. The reverse also holds: the Sun and Mercury, which really are conjunct in Cancer about a degree apart, stay together in D3 only because both are past 20 degrees. Had Mercury been at Cancer 19, it would have gone to Scorpio while the Sun went to Pisces.

The houses

The D3 Lagna is Leo, so house 1 is Leo and the rest follow in order: Virgo 2, Libra 3, Scorpio 4, Sagittarius 5, Capricorn 6, Aquarius 7, Pisces 8, Aries 9, Taurus 10, Gemini 11, Cancer 12. Gemini is the eleventh sign from Leo, so all four Gemini points are in house 11. Venus in Capricorn is in house 6, Jupiter in Aquarius in house 7, the Sun and Mercury in Pisces in house 8, and Ketu in Sagittarius in house 5. Houses 1, 2, 3, 4, 9, 10 and 12 are empty of grahas in this D3 chart. An empty house is not a missing result; ten points cannot fill twelve houses.

How to read each part of your result

The D3 sign of a point

The D3 sign is a restatement of where the point stands inside its Rasi sign. It adds no new astronomical information; the Rasi sign and the D3 sign together tell you which third of which sign the point is in, and nothing more. What the classical texts do with that restatement is treat the D3 sign as a place where the graha can be strong or weak in the usual way. BPHS Ch. 6 Sl. 42-53 counts a division as a good one for a graha when it falls in the graha's exaltation sign, its Mooltrikon sign or its own sign. Saravali Ch. 5 Sl. 31-33 says 'a planet in its own decanate confers virtues', and Ch. 12 Sl. 10-11 treats all the planets being in their own decanates as a condition that removes the birth-time evils that chapter lists.

In the worked chart no graha is in its own D3 sign: the Sun and Mercury are in Jupiter's Pisces, the Moon, Mars and Saturn in Mercury's Gemini, Jupiter in Saturn's Aquarius and Venus in Saturn's Capricorn. The calculator does not announce this either way; you can read it from the table of 36 above.

The D3 house of a graha

The house number is counted in whole signs from the D3 Lagna. It exists only because a birth time and place were supplied. The house numbers are the most time-sensitive part of the result, because they all move together whenever the D3 Lagna changes sign - on the sample day that happened every 30 to 46 minutes. The page reports the numbers and does not interpret them. If you want to study what each house stands for in the classical scheme, the house articles, starting with the third house, Sahaja Bhava, set out what BPHS assigns to each.

Points that keep their sign

The engine uses one check for every divisional chart: is the divisional sign the same as the Rasi sign? In the Navamsa that check is the classical vargottama condition, which Saravali Ch. 3 describes as making a person important in their circle. In D3 the same flag is raised under the same name, but its meaning is plainer. It marks a point in the first 10 degrees of its sign, and about a third of all points in all charts will carry it. Treat it as a description of position, not as a distinction. The Navamsa version, which depends on the sign's own nature as well as the degree, is explained in Navamsa, the second chart.

When the calculator declines

This calculator is registered as needing an Ascendant. If you give a date without a time, it returns no chart and says that the Ascendant needs a birth time as well as a place, and that without both there are no houses to read, 'so none are shown rather than estimated'. If you give a time but the place does not resolve to coordinates, it says the place is the missing piece. It never falls back to a noon chart or an assumed latitude. If you do not know your time, what to do when the birth time is unknown explains which readings survive and which do not.

What the classical texts do with the Drekkana

The Drekkana is used in the sources in four distinct ways. They are worth separating, because only one of them concerns siblings, and because this app implements some and not others.

1. Co-born

BPHS Ch. 7 Sl. 1-8 assigns one subject to each of the sixteen divisions: the physique from the Lagna, wealth from the Hora, 'happiness through co-born from Dreshkan', fortunes from the Chaturthamsa, children from the Saptamsa, spouse from the Navamsa, and so on. Co-born is the translator's word for brothers and sisters. The pairing of siblings with courage, which the summary on this page repeats, comes from the third house and not from Ch. 7 itself: BPHS Ch. 14 Sl. 1 opens its account of Sahaj Bhava by saying that if it is joined or aspected by a benefic, 'the native will be endowed with co-born and be courageous'. D3 is the third division and is read alongside the third house, so the two themes travel together. Ch. 14 goes on to bring Mars into several of its sibling combinations, which is why Mars is usually examined with this chart.

Notice what Ch. 7 does not say. It names the subject of the division and gives no rules for reading a D3 house layout sibling by sibling. BPHS's detailed sibling slokas are all written for the third house of the Rasi chart. This is one reason the calculator stops at placements: the primary source names the topic and leaves the method open, and this app does not fill gaps the source leaves.

2. A component of planetary strength

The second use has nothing to do with siblings. The Drekkana is one of the divisions across which a graha's strength is totalled. BPHS Ch. 7 gives it a different weight in each scheme.

This app's Vimshopaka Bala uses the sixteen-division scheme, so D3 carries 1 point of the 20. For the sample chart the D3 row of that calculation reads: the Sun in Pisces, a friendly sign, earns 0.625; the Moon in Gemini, friendly, 0.625; Mars, Venus and Saturn in neutral signs earn 0.5 each; Mercury in Pisces, its debilitation sign, earns 0; Jupiter in Aquarius, rated an enemy sign for this chart, earns 0. Those are small numbers because the weight is small - the Moon's total across all sixteen divisions is 10.88 and Jupiter's is 6. The point is that your D3 signs are already at work elsewhere in the app, quietly, as one input among sixteen.

BPHS Ch. 27 uses the Drekkana twice more inside Shad Bala. Sl. 2-4 make it one of seven divisions in Sapt Vargaj Bal, where a graha earns from 45 virupas (Mooltrikon) down to 2 according to its relationship with the sign it occupies in each. Sl. 6 defines a separate Dreshkan Bal: 'male, female and hermaphrodite Grahas, respectively, get a quarter Rupa according to placements in the first, second and third decanates'. Here the two texts in this library do not agree. Saravali Ch. 4 Sl. 38 says male planets are strong in the first decanate, female planets in the third and neutral planets in the second. The first decanate is common ground; the second and third are swapped. The D3 page shows neither version - it reports which third each graha is in, and that is the fact both rules start from.

3. The rising Drekkana

The third use concerns only the Ascendant: which third of the rising sign was on the horizon. BPHS Ch. 12 Sl. 12-14 and Saravali Ch. 4 Sl. 3-6 both use it to map the twelve houses onto the body. With the first decanate rising the count runs from the head (head, eyes, ears, nose, temple, chin, face); with the second, from the neck (neck, shoulder, arm, side, heart, stomach, navel); with the third, from the pelvis down to the foot. BPHS adds that the part already risen stands for the left side and the part yet to rise for the right, and Sl. 15 connects marks and scars with the grahas placed accordingly. This is reported here as what the texts say about bodily marks. It is not medical advice, and this app makes no health statements from it.

Saravali Ch. 41 Sl. 20 uses the rising decanate differently, to grade the Ascendant's own period in a dasha scheme: with a movable sign rising, the first decanate is auspicious, the second medium and the third poor; with a dual sign the order reverses; with a fixed sign the first is poor, the second auspicious and the third medium. And Saravali's final chapter, Ch. 50, gives a character sketch for birth in each of the 36 decanates, which the text places in the context of reconstructing a lost horoscope. The calculator applies none of these. In the sample the Ascendant is at Leo 2.33, so it is the first decanate of a sign that rose; that single fact is what any of these passages would start from.

4. Specialised rules

The remaining mentions are scattered. BPHS Ch. 39 Sl. 25 forms a Raj Yog when the Bhava, Hora and Ghatik Lagnas together with their Dreshkanas and Navamsas receive the aspect of one graha; this app does not compute those special Lagnas, so the rule is not among the yogas it detects. BPHS Ch. 78 Sl. 5-9, on lost horoscopy, reads the season of birth from the lord of the Drekkan in which a question's Lagna falls. BPHS Ch. 44 Sl. 38-40 and Saravali Ch. 47 Sl. 22 use the Drekkana of the eighth house - the 22nd counted from the rising one - in their passages on the end of life, and BPHS singles out four as serpent Dreshkanas (the second and third of Cancer, the first of Scorpio, the last of Pisces). Those passages exist and are named here for completeness. This app does not compute the 22nd Drekkana, does not label any part, and makes no statement on that subject anywhere.

Birth-time sensitivity, measured

The note above the fold says the D3 Lagna changes more often than the Rasi Lagna. Here is how often, for the sample birth. The engine was run every ten seconds across 14 August 1994 at Ahmedabad and each change of the D3 Lagna was recorded.

Across the whole day the D3 Lagna took 36 successive values, one for each third of each rising sign. The shortest spans were 30 minutes, while Pisces was rising in the evening; the longest was 45 minutes 40 seconds, while Scorpio was rising in the early afternoon. Those lengths belong to this latitude and this date; the same sweep at another place would give different ones, because signs do not rise at an even pace.

The sample birth at 06:42 falls about ten minutes after the D3 Lagna became Leo. Suppose the recorded time were eleven minutes late and the true birth was 06:31. The Rasi Lagna would be Cancer, in its last third, and the D3 Lagna would be Pisces. None of the grahas would change D3 sign, but every house number would. The four points in Gemini would be in house 4 and not house 11; the Sun and Mercury in Pisces would be in house 1 and not house 8; Venus would move from house 6 to house 11, and Ketu from house 5 to house 10. Now suppose the time were 35 minutes early and the true birth was 07:17. The Rasi Lagna is still Leo, so the Rasi chart looks unchanged - but the D3 Lagna is Sagittarius, the Gemini group is in house 7, and Ketu is in house 1.

That second case is the one to remember. A birth time can be good enough to fix the Rasi Lagna and still be wrong for D3. Conversely, D3 is three times more forgiving than the Navamsa, whose Lagna changes three times within each Drekkana. If your time comes from memory, or is rounded to the quarter or half hour, read the D3 signs with confidence and the D3 houses with caution. The article on the sub-lord and birth time works through the same problem for an even finer division.

The grahas move too, slowly

The Moon is the only graha likely to change D3 sign within a birth date. On the sample day it was in the last third of Libra, D3 Gemini, from midnight until 15:49, when it entered Scorpio and its D3 sign became Scorpio. Anyone born that day after 15:49 has a different D3 Moon from the sample person. The other grahas cover 10 degrees far more slowly and will only change D3 sign on a birth date if they happen to be sitting right at 0, 10 or 20 degrees.

Limits worth knowing before you rely on it

• Boundary degrees. A point printed at 9.98 or 10.02 degrees is within the margin by which sidereal positions differ between programs. The largest single cause is the choice of ayanamsa; the ayanamsa calculator shows the value this app uses for any date, and why apps disagree explains how a small offset moves a point across a line.
• Formula-based positions. This app computes positions from built-in formulas and does not claim an ephemeris-grade source; the methodology page states this plainly. For D3 the practical effect is confined to points close to 0, 10 and 20 degrees.
• One counting rule. The calculator implements the 1st-5th-9th rule as BPHS Ch. 6 and Saravali Ch. 3 state it. It offers no alternative scheme and no setting to change the rule.
• No interpretation. BPHS names siblings as the subject of this division but gives its detailed sibling rules for the third house of the Rasi chart. The calculator therefore does not turn a D3 layout into statements about brothers or sisters, their number or their welfare.

How D3 connects to the rest of the app

D3 is one of fifteen divisional charts the app computes from the same routine. Its nearest relatives are the Hora (D2), which halves the sign, and the Chaturthamsa (D4), which quarters it and steps through the kendras - the 1st, 4th, 7th and 10th signs - where D3 steps through the trines. Seeing the two side by side makes the logic of both clearer. The family charts that BPHS Ch. 7 lists next to it are the Saptamsa (D7) for children and the Dwadasamsa (D12) for parents.

If you have an account, the same D3 computation is included in the full Kundali reading whenever your profile has a birth time, alongside the Rasi chart it is derived from; you can also build that Rasi chart on its own with the free birth chart tool. The sign pages - for the worked example, Leo for the D3 Lagna and Gemini for the cluster - describe what the classical texts say of each sign, which applies to a sign wherever it turns up. And the accuracy page sets out how the app treats readings that depend on an uncertain birth time.

Frequently asked questions

Is a Drekkana the same thing as a decanate or a decan?

Yes, as a division. All three words mean a third of a sign, 10 degrees wide; the Saravali translation used here says decanate throughout, and the BPHS translation says Dreshkan or Drekkan. What makes the Indian Drekkana specific is the rule for which sign each third is assigned to: the sign itself, the fifth from it and the ninth from it, as BPHS Ch. 6 Sl. 7-8 and Saravali Ch. 3 Sl. 14 both state.

Can I work out my D3 sign without the calculator?

If you know a point's sidereal sign and degree, yes. Under 10 degrees, the D3 sign is the same sign. From 10 up to 20, count five signs starting with the sign itself. From 20 up to 30, count nine. Or look the sign up in the table of 36 on this page. What you cannot do by hand without real effort is find the sidereal degree in the first place, especially the Ascendant's.

Why do several of my planets share one D3 sign when they are in different signs in my birth chart?

Because each D3 sign collects three different thirds - one from each sign of its trine group. In the worked example, Mars in the first third of Gemini, Saturn in the second third of Aquarius and the Moon and Rahu in the last third of Libra all land in Gemini. It is a consequence of the counting rule and does not mean the grahas are close together in the sky.

Does the D3 chart tell me how many siblings I have?

This calculator does not, and it is not designed to. BPHS Ch. 7 names 'happiness through co-born' as what the Drekkana is consulted for, but its counting rules for siblings are given in Ch. 14 for the third house of the Rasi chart, and they are conditional combinations, not a formula. The page reports placements only. The third house article covers what Ch. 14 says.

My birth time is approximate. Which parts of the result can I still use?

The D3 signs of the Sun, Mars, Mercury, Jupiter, Venus, Saturn and the nodes are almost never affected by an hour either way. The Moon's D3 sign changes roughly every 18 hours, so it is usually safe too unless the Moon is near 0, 10 or 20 degrees. The D3 Lagna and every house number are the fragile part: on the sample day the D3 Lagna changed every 30 to 46 minutes.

Is the D3 Lagna always related to my Rasi Lagna?

Yes. By the counting rule it is always the Rasi Lagna's own sign, the fifth from it or the ninth from it - never any of the other nine signs. Which of the three depends on whether the rising degree is in the first, second or last 10 degrees of the sign. A Leo Ascendant can only have a Leo, Sagittarius or Aries D3 Lagna.

Does this app use my D3 chart anywhere else?

Yes, in two places the code shows. The Vimshopaka Bala score counts the dignity of each graha's D3 sign as 1 of its 20 points, following BPHS Ch. 7 Sl. 21-25, and it does this even for a chart without a birth time because graha D3 signs do not need an Ascendant. And the signed-in Kundali reading includes the full D3 chart whenever a birth time is on the profile.

BPHS and Saravali give different rules for Drekkana strength. Which one is right?

The two translations in this library genuinely differ. BPHS Ch. 27 Sl. 6 gives male, female and hermaphrodite grahas their quarter Rupa in the first, second and third decanate in that order; Saravali Ch. 4 Sl. 38 gives male planets the first, female planets the third and neutral planets the second. We report both and do not pick a winner. The D3 calculator sidesteps the question because it shows only which third each graha occupies, which both rules accept as the starting fact.