Dwadasamsa Chart Calculator (D12)

Cast your Dwadasamsa (D12), the parents divisional chart of Vedic astrology, from date, time, and place of birth. The tool computes your D12 Lagna with a birth-time-confidence check, every planet’s D12 part, sign and house with its BPHS presiding deity, and renders the chart in North or South Indian style. Uses the sidereal Lahiri ayanamsa, the same engine as our Kundli.

100% private - the D12 calculation runs entirely in your browser. No birth data sent anywhere.

Enter birth details

Supports 1900 onwards for better calculation reliability.

Birth time matters more here than in any other varga we ship: at 2.5 degrees per division, your D12 Lagna changes about every 10 minutes on average, against the ~2-hour D1 Lagna.

Related Tools

Quick facts

Chart / harmonicD12 (Dwadasamsa), the twelfth divisional chart
Division size2.5 deg (twelve parts per sign)
Start-sign ruleThe sign itself, then counting forward (BPHS Ch. 6, 15)
Presiding deitiesGanesha, Ashwini Kumara, Yama, Sarpa - repeating three times
Classically read forParents (BPHS Ch. 7 varga-use verse)
D12 Lagna sensitivity~10 min of birth time per part - the fastest varga we ship
Same-sign geometryPart 1 self-maps: one twelfth of each sign's span, evenly
Near-boundary flag bandAbout 24% of the zodiac, against ~6% on the D3 - expect it often
Near-boundary jumpOne sign at a part edge; TWO signs at a whole-sign edge
InputsDate, time, and place of birth
EngineMeeus VSOP87 + Lahiri ayanamsa; Rahu/Ketu = mean node (same engine as Kundli)
Privacy100% client-side; no birth data leaves your browser

What is the Dwadasamsa (D12) chart?

The Dwadasamsa - also spelled Dvadasamsa or Dwadashamsa - is the twelfth of the sixteen divisional charts (Shodasavarga) described in the Brihat Parashara Hora Shastra. Where the birth chart (D1) maps the whole life, each varga zooms into one domain, and the classical varga-use verse assigns the Dwadasamsa to parents.

Like every varga, the D12 is a derived chart: it takes each planet’s exact sidereal longitude from the birth chart and re-maps it by finer divisions of 2.5 deg. Nothing new is observed in the sky; the varga re-reads the same positions at higher resolution - and at 2.5 deg this is the finest resolution of any chart we publish, which is why precise birth details matter here more than anywhere else on the site.

How the D12 is calculated (and its four deities)

Each 30-deg sign is divided into twelve parts of 2.5 deg. The rule is simple and the same for every sign - there is no odd/even split: the first part maps to the sign itself, and each following part advances one sign, so the twelve parts run through the whole zodiac and finish on the twelfth sign from the start. Each varga in the family carries its own rule - the Navamsa keys on movable/fixed/dual, the Dasamsa and Saptamsa fork on odd/even, the Drekkana steps in trines, and the Trimsamsa abandons equal parts altogether - so the D12’s plain forward count is the simplest rule in the family.

The same BPHS passage names four presiding deities whose presidentship repeats three times across the twelve parts, in this order:

PartDegrees in signMaps toPresiding deity
10.0 - 2.5 degThe sign itselfGanesha
22.5 - 5.0 degThe 2nd sign from itAshwini Kumara
35.0 - 7.5 degThe 3rd sign from itYama
47.5 - 10.0 degThe 4th sign from itSarpa
510.0 - 12.5 degThe 5th sign from itGanesha
612.5 - 15.0 degThe 6th sign from itAshwini Kumara
715.0 - 17.5 degThe 7th sign from itYama
817.5 - 20.0 degThe 8th sign from itSarpa
920.0 - 22.5 degThe 9th sign from itGanesha
1022.5 - 25.0 degThe 10th sign from itAshwini Kumara
1125.0 - 27.5 degThe 11th sign from itYama
1227.5 - 30.0 degThe 12th sign from itSarpa

Methods note: the deity names are given as the classical text gives them, without added interpretation. The consulted translation prints “Ganesh” and “Ashvini Kumar”; we use the common spellings Ganesha and Ashwini Kumara.

D12 Lagna and birth-time precision

The ascendant crosses one dwadasamsa in roughly 10 minutes of clock time on average - the fastest in our varga family, quicker than the Dasamsa’s ~12 minutes, the Saptamsa’s ~17 or the Drekkana’s ~40, and a long way from the two hours the D1 Lagna spends in a sign. The exact interval varies with rising sign and latitude (oblique ascension), so instead of quoting only the average, this tool computes your chart’s distance to the nearest D12 Lagna boundary in minutes and says so plainly. If your birth time is recorded to the nearest quarter hour, the D12 house framework is genuinely uncertain, and the tool will say so.

Planet placements have their own fragility near a division edge, and here the honest number is worth stating: this tool flags any planet within about 0.3 deg of an edge, and on a 2.5-deg division that band covers roughly 24 per cent of the whole zodiac - against about 6 per cent on the 10-deg Drekkana. So seeing several planets flagged is normal and is not a sign of a bad chart. That 0.3 deg figure is a conservative division-edge proximity heuristic we carry across our varga tools, not a certified accuracy bound and not a birth-time claim. One quirk worth knowing: a body crossing an ordinary part edge moves one sign, but a body crossing a whole-sign edge moves two D12 signs, so the tool names both alternatives instead of leaving you to work them out.

How the D12 is classically read

The Brihat Parashara Hora Shastra’s varga-use verse assigns the Dwadasamsa to parents. Practitioners look at the D12 Lagna and its lord, and at the 4th and 9th houses from the D12 Lagna, reading the chart together with the D1’s own houses - the varga refines the birth chart rather than overriding it, the same relationship the Navamsa (D9) has with marriage significations and the Dasamsa (D10) with career.

All of this is descriptive tradition, not prediction. This page makes no claims about your parents, their health, or their lives - the classical text pins the domain to parents, and nothing here goes beyond that.

What this version leaves out

This version computes the D12 chart, houses (whole-sign from the D12 Lagna), the BPHS presiding deities, and the birth-time-confidence checks. It does not interpret the chart, does not derive the separate mother-and-father readings some schools take from the D12, and it ships no predictions and no remedies.

Frequently Asked Questions

What is the Dwadasamsa (D12) chart?

The Dwadasamsa - also spelled Dvadasamsa or Dwadashamsa - is the twelfth divisional chart (varga) of Vedic astrology: each 30-deg sign is divided into twelve parts of 2.5 deg, and every planet is re-mapped to a new sign based on which part it occupies. The classical varga-use verse in the Brihat Parashara Hora Shastra assigns this chart to parents, which is why it is commonly called the parents chart. It is read alongside the birth chart (D1), not instead of it.

How is the D12 chart calculated?

Each sign is split into twelve parts of 2.5 deg. The first part maps to the sign itself, and the rest count forward one sign per part - so the twelve parts of a sign run through all twelve signs and end on the twelfth sign from it. In Taurus, for example, the parts run Taurus, Gemini, Cancer and so on, ending in Aries. The rule is the same for every sign: there is no odd/even split and no movable/fixed/dual split.

Who are the presiding deities of the twelve dwadasamsas?

The Brihat Parashara Hora Shastra names four - Ganesha, the Ashwini Kumaras, Yama, and Sarpa - and says the presidentship repeats three times in that order across the twelve parts, identically for every sign. The consulted translation prints them as Ganesh, Ashvini Kumar, Yama and Sarpa; we use the common ASCII spellings. This tool shows the deity for each planet's part; it does not attach any predictive meaning to them, because the classical text assigns the names without interpretation.

Why does exact birth time matter so much for the D12?

More than for any other varga we publish. The ascendant moves through one dwadasamsa (2.5 deg) in roughly 10 minutes of clock time on average, against about two hours for a whole sign in the birth chart, so an error of even a quarter of an hour can shift your entire D12 house framework. This tool reports how many minutes your entered time sits from the nearest D12 Lagna boundary, so you can judge how much weight the chart deserves.

The tool flags a lot of my planets as near a boundary. Is something wrong?

No - that is the honest arithmetic of a fine division. We flag any planet within about 0.3 deg of a division edge, and on a 2.5-deg division that band covers roughly 24 per cent of the whole zodiac, against about 6 per cent on the 10-deg Drekkana. So on the D12 the flag is common rather than exceptional. It marks a placement that a slightly different birth time or ephemeris could move, not an error and not a problem with your chart.

What does it mean if a planet is in the same sign in D1 and D12?

The planet keeps the same sign context in both charts. It is not special: the first dwadasamsa of every sign maps back to the sign itself, so under a uniform-within-sign model a same-sign placement covers one of the twelve 2.5-deg parts - one twelfth of each sign's span, evenly for all twelve signs. (The classical term vargottama refers to the D1/D9 correspondence, not to D12.)

How is the D12 different from the 4th house of my birth chart?

The 4th house of the D1 is one house among twelve in the natal chart, classically associated with mother, home, and comfort; the Dwadasamsa is an entire twelve-sign chart derived from finer 2.5-deg divisions, read for the parental domain at higher resolution. Practitioners read the two together - the varga refines the birth chart and does not override it, and it cannot promise what the birth chart does not.

Does this show the North Indian or South Indian chart style?

Both - use the North Indian (diamond) / South Indian (square) toggle above the chart; both draw the same D12 (Dwadasamsa) placements. In the North Indian format the houses are fixed with the Lagna at the top and the signs rotate; in the South Indian format the signs are fixed in the grid and the ascendant is marked in its box. Pick whichever regional format is more familiar.

Does this tool predict anything about my parents?

No. It computes the classical D12 chart and reports what traditional sources say the chart is consulted for - the varga-use verse assigns it to parents. It makes no predictions about your parents, their health, their lifespan, or your relationship with them, and it offers no remedies.

Sources

  • Parashara, Brihat Parashara Hora Shastra, Ch. 6, 15, for the division size, the starting sign and the four presiding deities: “The reckoning of the Dvadashahs (one twelfth of a Rasi, or 2 1/2 degrees each) commences from the same Rasi. In each Rasi the presidentship repeats thrice in the order of Ganesh, Ashvini Kumar, Yama and Sarpa.” Ch. 7, 1-8 for the varga-use assignment (“parents from Dvadashahs”). Consulted through the English translation in the R. Santhanam lineage (full-text scan at archive.org, Parashara Hora Sastra, accessed 26 July 2026).
  • Bharathi R Ram (the same page’s breadcrumb spells it Barathi), “Dwadasamsa - D12” (Astro-Vision), published 11 August 2020, accessed 26 July 2026, for the counting DIRECTION with a worked example: “In every sign, it commences from the same and runs to the 12th sign from it. Thus in Taurus, it will commence from this sign and will remain up to Aries, the 12th sign from it.” Cited separately from the verse because the verse fixes the size, the start sign and the deity order but does not by itself settle whether the count runs forward.
  • Parity (2026-07-26): the scheme was checked against JHora 8.0’s Dwadasamsa D-12 chart for a pinned fixture - 15 Jan 1990, 12:00 IST, New Delhi - under Traditional Lahiri with the mean node, and matched all ten bodies including both nodes and the Lagna. That fixture does not occupy every one of the twelve parts; the parts it misses are covered by our own exhaustive test matrix against the sources above rather than by the capture.
  • N.C. Lahiri, Indian Astronomical Ephemeris (Rashtriya Panchang), for the sidereal Lahiri ayanamsa.
  • Jean Meeus, Astronomical Algorithms, 2nd ed., 1998 (VSOP87), for the planetary positions.

This page is the canonical surface for these terms: Dwadasamsa, Dvadasamsa, Dwadashamsa, Dwadashamsha, Dvadashamsa, and D12 chart. They all refer to the twelfth divisional chart described above.

Cultural / informational purposes only
Dwadasamsa results on this page are for cultural and informational purposes only. They describe a sidereal Vedic astrology reference frame, not predictions about your parents or family, and are not a substitute for professional advice. Last updated: July 2026.