Shodasha means sixteen, and the Shodashamsa cuts each sign into sixteen parts. The chart is also called the Kalamsa in some books. The name Shodashavarga for the whole set of sixteen charts is a separate use of the same word, which can cause confusion: here it means the sixteenth division only.
What the Shodashamsa is read for
The tradition assigns this chart to vehicles, material comforts and the general feeling of ease or discomfort in daily living. It is the chart astrologers consult about cars and other conveyances, about household comforts and about contentment with what one has. The fourth house of the Rashi chart, which stands for home, vehicles and inner peace, is the main reference, and Venus, the planet of comforts and conveyances, is the natural significator (karaka).
Since “happiness” is a broad word, teachers differ on what the D16 adds to the fourth house. The fair summary is that it is read as an extra layer for the pleasures and conveniences of life, and for how a person experiences them, and not as a promise of any particular purchase. A planet well placed in this chart is read as supporting ease in these matters, and one poorly placed as asking for more patience.
How the Shodashamsa is calculated
The Parashari rule used by the divisional charts calculator splits each sign into sixteen parts of 1 degree 52 minutes 30 seconds (1.875 degrees). For a movable sign (Aries, Cancer, Libra, Capricorn) the count begins at Aries. For a fixed sign (Taurus, Leo, Scorpio, Aquarius) it begins at Leo. For a dual sign (Gemini, Virgo, Sagittarius, Pisces) it begins at Sagittarius. Each following part takes the next sign in order, and since there are sixteen parts and only twelve signs, the sequence goes round the zodiac once and then continues into a second round for the last four parts.
| Sign divided | Part 1 falls in | Last part (16) falls in |
|---|---|---|
| Aries | Aries | Cancer |
| Taurus | Leo | Scorpio |
| Gemini | Sagittarius | Pisces |
| Cancer | Aries | Cancer |
| Leo | Leo | Scorpio |
| Virgo | Sagittarius | Pisces |
| Libra | Aries | Cancer |
| Scorpio | Leo | Scorpio |
| Sagittarius | Sagittarius | Pisces |
| Capricorn | Aries | Cancer |
| Aquarius | Leo | Scorpio |
| Pisces | Sagittarius | Pisces |
Take a planet at 20°00′ of Taurus. Each part is 1°53′ long, so this position lies in part 11 (from 18°45′ to 20°38′). By the rule above, part 11 of Taurus is Gemini, so the planet sits in Gemini in D16.
The table gives the sign of the first and last part for each sign. Parts 13 to 16 repeat the signs of parts 1 to 4. For example, in a movable sign the first part is Aries and the thirteenth is Aries again, and the sixteenth is Cancer, three signs on from the first.
A chart that is hard to cast by eye
Each part is less than two degrees, and the ascendant crosses that distance in about seven and a half minutes. The D16 Lagna is therefore sensitive to the birth time. The D45 uses the same starting signs as the D16, and the D20 uses them with the starts for fixed and dual signs swapped, so the three are easy to confuse by hand. The table above is the surest way to check a result.
Where schools differ
The movable, fixed and dual rule with starts at Aries, Leo and Sagittarius is the one found in Brihat Parashara Hora Shastra and followed by most teachers who use the chart. Some modern writers list different starting signs, so it is worth checking the scheme when two programs disagree. The calculator prints its rule under each result for this reason. Interpretation also differs: some astrologers read the D16 more for the whole quality of daily comfort, others mainly for vehicles.
How much weight teachers give it
In the commonly quoted Vimshopaka weights the Shodashamsa carries 2 out of 20 in the Shodashavarga, which is a large share compared with most of the minor charts: only the D1, D9 and D60 have more. It is not in the Shadvarga or Saptavarga, but it is in the Dashavarga. In day-to-day practice, though, it is not among the most consulted charts, and many astrologers open it only for a question about conveyance or domestic comfort.
As always, the D16 serves the main chart. The fourth house, its lord, Venus and the Moon are examined in the Rashi chart first, using the site’s house guides, and the dasha that is running tells you when the theme is active. A practical decision, such as buying a vehicle, depends on budget, need and safety, and an astrological view of the matter is one consideration among several.
Reading your own Shodashamsa
Choose D16 in the calculator, enter your details and look at the Lagna, the position of Venus and the Moon, and the lord of the fourth house from the Rashi Lagna. Compare with the Rashi chart. For timing, the Mahadasha explained shows how periods are read.
The preceding chart is the Dwadashamsa (D12) and the next is the Vimshamsa (D20).
Frequently asked questions
↳ What is the D16 chart used for?
Tradition reads it for vehicles, comforts and the general feeling of ease in daily life. Venus and the fourth house of the Rashi chart are the main reference points.
↳ How is the Shodashamsa calculated?
Each sign is divided into sixteen parts of 1 degree 52 minutes 30 seconds. The count starts at Aries in a movable sign, at Leo in a fixed sign and at Sagittarius in a dual sign.
↳ Is the Shodashamsa the same as the Shodashavarga?
No. The Shodashamsa is the single chart that divides each sign into sixteen parts, while the Shodashavarga is the whole set of sixteen divisional charts from D1 to D60.
↳ Can the D16 tell me whether to buy a car?
No. It describes tendencies around comfort and conveyance and cannot decide a purchase. Budget, need and safety are the real grounds for such a decision.
↳ Why does the D16 need an accurate birth time?
Each part is under two degrees, and the ascendant crosses that in about seven and a half minutes. A small error in the birth time can change the Lagna of the chart.