What is a Dasamsa (D10) chart and what is it read for?
A Dasamsa (दशांश, a tenth part) is one of the sixteen divisional charts Parashara sets out in the Brihat Parashara Hora Shastra. Each of the twelve signs is divided into ten equal parts of 3°, and each part is assigned to a sign; collect the assignment for every graha and for the ascendant and you have a second chart, drawn like the first but standing for one department of life. The department the classical assignment gives the D10 is karma: work, profession, authority and public standing. In practice astrologers read the tenth house of the birth chart first and then open the D10 to see the same question in more detail. The varga is a magnifying glass over one house, never a replacement for the chart it came from.
A varga has its own lagna and its own twelve houses
This is the point most readers miss. The D10 ascendant is computed from the birth ascendant's longitude by the same division rule, and every house in the D10 is counted from that sign, not from the rashi lagna. A graha in the same sign in both charts can sit in quite different houses. The table on this page prints the D10 house explicitly so the two are never confused.
Degrees mean nothing inside a divisional sign
A division maps a 3° slice of the zodiac onto a whole 30° sign, so the degree a graha would notionally hold in the D10 is an artefact of the arithmetic rather than a position anything is read from. That is why the chart is drawn without degrees here and why vargottama (the same sign in both charts) is flagged instead. Software that prints D10 degrees is printing noise.
How is the D10 calculated, and what is the exact rule?
Take a graha's sidereal longitude, on the Lahiri (Chitrapaksha) ayanamsha, and find its degrees within its own sign. Divide by 3 to get which of the ten parts it falls in, numbered from zero. Then count that many signs forward from a starting sign, and the starting sign is what the rule turns on: for an odd sign (Aries, Gemini, Leo and so on), the count starts from the sign itself; for an even sign it starts from the 9th sign from it. So 0°–3° of Aries is Aries, and 0°–3° of Taurus is Capricorn, the 9th from Taurus. This is the classical Parashari rule and it is not the same as the uniform cyclic division some libraries use, which simply counts tenths from Aries and produces a different chart.
Odd and even are counted from Aries
Aries is the first sign and therefore odd, Taurus the second and therefore even, and so on alternating round the zodiac. The odd/even split here is positional and has nothing to do with element or modality, which drive other divisions (the D16 keys off modality, for instance). Mixing the two up is the error that produces a plausible-looking D10 that disagrees with every classical source.
Why the 9th sign for even signs
Parashara states it rather than deriving it, and commentators explain it by the tenth part of an even sign being read from the ninth, a dharma house, so that the two halves of the zodiac are not treated identically. Whatever the reasoning, it is the rule the classical text gives and the one this engine implements. The practical consequence is that a graha's D10 sign is rarely the sign a reader would guess.
What does the 10th house of the D10 show?
It is the house the chart is named for, and where writers who read the D10 look for the work itself. The result names the sign of your D10 tenth house, its lord and where that lord stands within the D10, and lists any grahas occupying it. A house with no tenant is entirely ordinary and is read through its lord. What the tradition does not do is read a profession off a single house. The D10 is consulted alongside the tenth house of the birth chart, the tenth lord, the Amatyakaraka in Jaimini reading, and the running dasha; a page that turned one house into a job title would be inventing a technique rather than reporting one. Treat the D10 as detail added to a reading, not as a reading on its own.
Can a D10 chart tell me which career to choose?
No, and it is worth being plain about it. The classical texts read the D10 for the character of work and standing (whether authority is carried, whose approval matters, how public the role is) in the vocabulary of a world with a quite different economy. They do not contain job titles, and nothing about a divisional placement has been shown to select an occupation. What the chart can honestly give you is the tradition's own reading of one department of life, with the working shown, which you can then weigh against everything you already know about yourself. Any site that reads a salary or a designation off a D10 has left the tradition behind and is filling the gap with confidence.
What the texts actually describe
Classical descriptions of the tenth house and its varga run to themes: service or independence, work under authority or over it, learning as a livelihood, work connected with land, with speech, with metal. These are categories from an older economy and they map onto modern occupations loosely at best. Reading them as categories is using the source; reading them as a careers service is not.
The dasha decides timing, not the varga
A divisional chart is static: it says what the tradition reads in a department of life, with no clock attached. Questions about when something is read to unfold belong to the dasha systems, and our Vimshottari calculator sets the sequence out with its balance at birth. Using a varga to answer a timing question is a category error that produces confident nonsense.
Why does the D10 need an exact birth time?
Because a tenth division multiplies every error by ten. The birth ascendant moves through a whole sign in roughly two hours, which means it crosses a 3° dasamsa slice in about twelve minutes, so a birth time out by a quarter of an hour can land the D10 lagna in a different sign, and every house in the chart is counted from there. The faster-moving grahas are affected too, though far less: the Moon crosses a dasamsa slice in about five and a half hours. The slow grahas will not move at all. If your recorded time is rounded to the nearest hour, the planetary placements in the D10 are mostly sound and the D10 ascendant is a guess, and that is the half of the chart everything else is measured from.
Twelve minutes moves the D10 lagna
The arithmetic is simple enough to check: two hours for 30° of ascendant, ten slices in that sign, so twelve minutes a slice on average. Rising times differ by sign and by latitude, so the real figure varies, but the order of magnitude holds everywhere. A birth certificate recorded to the minute is genuinely worth more here than on a page that only needs the Moon's sign.
Rectification is not something a calculator does
Where the time is unknown, astrologers rectify, working backwards from recorded events to a time that fits, a slow manual process requiring judgement and a willingness to be wrong. No calculator on this site does it, and a site that offers an instant rectified time is offering a guess with a confident face. Better to know the D10 lagna is uncertain than to be handed a false one.
How does the D10 differ from the D9 and the other vargas?
By its division rule and by the department it is assigned. The D9 navamsa cuts each sign into nine parts of 3°20' and is read for marriage and the second half of life; it is the varga weighted most heavily after the birth chart. The D7 saptamsa cuts each sign into sevenths and is read for children. The D10 cuts into tenths for work. Sixteen such charts make up the Shodasavarga, and the full kundli on this site draws all of them. The rules genuinely differ from one to the next (some count from the sign itself, some from the ninth, some key off modality), so a single arithmetic shortcut applied to all sixteen is wrong for most of them.
Is the D10 the same as the tenth house of my birth chart?
No. The tenth house of the birth chart is one of twelve houses in the rashi chart; the D10 is a separate chart of twelve houses of its own, derived from every graha's position rather than from that one house. They answer the same question at different resolutions, and classical practice reads the birth chart first. A strong tenth house with a weak D10, or the reverse, is a normal result and is read as a tension rather than as a contradiction to be resolved. Houses here are whole-sign, both in the rashi chart and in the D10; a cusp-based system such as Bhava Chalit or Placidus is not applied to a divisional chart in classical practice.
How this is calculated
Nirayana rashis with the Lahiri (Chitrapaksha) ayanamsha and whole-sign bhavas, computed to arc-second accuracy. Sunrise and sunset are the ones almanacs show, the Sun's upper edge with refraction, so the daily windows agree with the calendars you compare them with. More on our method.