Parashari Hora D2: Calculate the Two Halves of Every Sign

How is a Parashari D2 Hora sign calculated?

This guide calculates the destination sign from a stated longitude. It includes the complete lookup table, twenty original checks and a way to investigate uncertain inputs. The arithmetic describes a traditional astrological convention; a correct calculation does not establish that a prediction based on it will be true.

Name the Hora convention before comparing charts

The Hora discussion in chapter six of the Brihat Parashara Hora Shastra describes the half-sign division and the reversal of the Sun–Moon order between odd and even signs. The common two-sign implementation places the Sun's Hora in Leo and the Moon's Hora in Cancer. That is the convention used throughout this article.

P. V. R. Narasimha Rao's paper linked below discusses this familiar approach alongside alternative Hora constructions. Its comparison matters: the label “D2” alone does not identify every software setting. A chart using all twelve signs may be applying a different declared method rather than making a simple arithmetic error.

Before evaluating a disagreement, write down the actual rule. Keep the zodiac reference, any ayanamsha setting and the original longitudes consistent. Only then compare natal sign, half, Hora lord and destination. If those intermediate fields are missing, two final charts can disagree without revealing where their calculations first separated.

Two halves, twenty-four portions and two destinations

One sign spans 30°. Its two halves are 0° up to but not including 15°, and 15° up to but not including 30°. In angular units, a half contains 900 arcminutes or 54,000 arcseconds. These are units of angle, not clock time.

Across twelve natal signs there are twenty-four half-sign portions. In this particular mapping they have only two destination signs, Cancer and Leo. “Twenty-four portions” therefore does not mean a chart with twenty-four houses, and “two destinations” does not mean that the original sky contains only two signs.

The Sun and Moon are the lords of the two Hora types. Any body's longitude, or a calculated Ascendant longitude, can be classified by the same rule. A Sun Hora does not mean that the input body itself must be the Sun. Likewise, Moon Hora is not a claim about the Moon being physically present beside that body.

A complete table for all twelve natal signs

The ordinal column begins with Aries as one. Odd means 1, 3, 5, 7, 9 and 11; even means 2, 4, 6, 8, 10 and 12. This is not a classification by movable, fixed or dual modality. It also has nothing to do with odd-numbered dates, daytime versus night, or the hour at which the chart was opened.

Notice the alternating rows. Aries begins with Sun Hora, Taurus with Moon Hora, and Gemini with Sun Hora again. Reading this pattern directly is often easier than memorizing a separate statement for every sign.

A five-step calculation from a full longitude

1. Normalize the full longitude L into 0° ≤ L < 360°. A full turn of 360° returns to 0°.
2. Identify the natal sign and the remaining within-sign angle d, where 0° ≤ d < 30°.
3. Choose the first half if d < 15°; otherwise choose the second half.
4. Use the natal sign's one-based ordinal to select the odd or even row of the Sun–Moon rule.
5. Map Sun Hora to Leo and Moon Hora to Cancer, keeping the original longitude beside the result.

A compact implementation can use a zero-based sign index s, with Aries = 0. The natal sign is odd-numbered when s is even. The Hora is solar when “d < 15” and “s is even” have the same truth value. This indexing detail prevents the common mistake of reversing every result.

Worked pair: Libra 26°45′ and Scorpio 11°45′

Take an invented full longitude of 206°45′. It lies in Libra, the seventh sign, with d = 26°45′. Libra is odd-numbered and the angle is in its second half. The result is Moon Hora, mapped to Cancer.

Now use 221°45′. This is Scorpio, the eighth sign, with d = 11°45′. Scorpio is even-numbered and the angle is in its first half. The result is again Moon Hora and Cancer. The two inputs are 15° apart, yet their D2 destination sign agrees because they reach the same Hora type through different rows of the table.

To check the notation, 26°45′ equals 26.75°, not 26.45°. Convert the forty-five arcminutes by dividing by sixty. Retaining the original degrees-and-minutes form alongside the decimal value makes accidental conversions easier to spot.

Twenty boundary checks, including the zodiac wrap

The first three entries isolate the 15° boundary in Aries. The values 14°59′59″ and 15°00′00″ are one arcsecond apart but belong to different halves. Repeat that check in Taurus: the boundary is the same size, while its Sun–Moon direction is reversed.

The 345° entries test the second half of Pisces rather than another Aries example. The final row then treats exactly 360° as 0° Aries. Keeping both tests prevents a normalization error from hiding behind an otherwise correct half-sign rule. These are artificial test coordinates, not a collection of birth charts.

A natal-sign boundary can leave the D2 sign unchanged

Aries 29°59′59″ is in Moon Hora. One arcsecond later, the longitude is Taurus 0°00′00″, which is also in Moon Hora. The natal sign and half number change, but the D2 sign remains Cancer.

The same structure occurs at the next boundary: Taurus ends in Sun Hora and Gemini begins in Sun Hora, so both sides map to Leo. Alternation makes this true at every natal-sign boundary, including Pisces to Aries. In contrast, crossing the 15° midpoint within any sign switches the destination.

This is a useful diagnostic property of the two-sign rule. It is not a reason to ignore natal-sign changes in the rest of a chart. A stable D2 destination reports only that this particular mapping has not changed; other chart factors can change at the same input boundary.

Check whether the plausible input interval crosses a midpoint

The second interval runs from Aries 14°59′30″ through 15°00′10″. Both Hora types must be retained. Reporting only the result at its centre would hide the fact that the input uncertainty permits another destination.

The third interval crosses into Taurus but stays in Moon Hora throughout. This illustrates why “near a boundary” needs a named boundary: a natal-sign edge and a Hora midpoint do not behave identically. These examples assume inclusive interval endpoints and invented angular uncertainty; they do not estimate the reliability of a birth time.

If a calculator rounds 14°59′59.6″ to 15°00′00″ on screen, the underlying coordinate remains below the midpoint. Calculate from the available unrounded value and describe the display precision separately. Additional digits in the output cannot create precision that the original observation or birth record never supplied.

Why “multiply the longitude by two” is a different rule

Consider Taurus 7°30′, or full longitude 37.5°. Under the convention here it is the first half of an even sign: Moon Hora, Cancer. A full-longitude second harmonic instead gives 2 × 37.5° mod 360° = 75°, in Gemini.

The harmonic successively sends the two halves of Aries to Aries and Taurus, the two halves of Taurus to Gemini and Cancer, and so on. It therefore uses all twelve signs. It must not be substituted silently for the two-sign Sun–Moon mapping just because both divide natal signs into halves.

This guide specifies destination signs, not degrees within those destination signs or a complete house calculation. If another display includes transformed degrees, house positions or a strength score, obtain the additional rules before claiming to reproduce it.

D2 Hora is different from the daily planetary-hour tool

A daily Hora schedule divides the daylight and night intervals into planetary hours and assigns their lords in a repeating order. It requires a place, date and local sunrise and sunset boundaries. The daily Hora guide explains that time-based calculation.

A D2 Hora placement instead starts from a body's zodiac longitude and the natal-sign half. It does not ask which planetary hour is currently running. Changing the observation date on a daily Hora calendar is not a method for changing the D2 mapping of an already specified longitude.

The shared word can make search results confusing. Include “D2 chart” when asking about this sign division, and “planetary hour” or “daily Hora” when asking about a time interval. Keeping the input units visible usually resolves the ambiguity immediately.

What this calculation can and cannot tell you

Hora charts are traditionally discussed in connection with resources and wealth. That interpretive association is distinct from the mathematical result. A placement in Leo or Cancer does not by itself establish anyone's income, spending behaviour or future circumstances.

Because many longitudes share either destination, two bodies appearing in the same D2 sign need not be near each other in the natal sky. Do not describe that agreement as a measured physical conjunction. Preserve their original longitudes and examine any natal relationship separately.

The useful achievement of this worksheet is reproducibility: someone else can take the same inputs and stated convention and check the classification. It is not a financial decision rule or a test of personal worth.

A six-field worksheet for comparing two calculators

1. Record the named Hora method and its destination-sign rule.
2. Record zodiac reference and ayanamsha, where applicable.
3. Copy the full longitude at its available precision.
4. Write natal sign, ordinal and within-sign angle.
5. Write half number, Hora lord and destination sign.
6. Test an exact midpoint and a nearby plausible input before comparing interpretations.

If the starting longitudes disagree, investigate that upstream difference first. If they agree but the halves differ, inspect rounding and endpoint handling. If the halves agree but destinations differ, compare conventions and odd/even indexing.

Continue with degrees and subdivisions or D60 and input sensitivity, then inspect the Kundli tool with your calculation notes beside it.

Frequently asked questions