How charts are calculated

Traditions differ on some of the choices below. If another program gives you a slightly different result, one of these settings is usually the reason.

Astronomy

Planet positions: Computed with astronomy-engine and checked against Swiss Ephemeris: across 24 test births in 8 countries, positions agree within 11 arcseconds, and sign, nakshatra, pada, house and retrograde flags are identical.
Zodiac and ayanamsa: Sidereal zodiac with the Lahiri (Chitra Paksha) ayanamsa by default. Other ayanamsas are available in the calculators.
Rahu and Ketu: Mean node by default; Ketu is always exactly opposite Rahu. Mean and true node differ by up to about 1.5°, and our mean node sits within about 12 arcseconds of Swiss Ephemeris because of a small nutation convention.
Time zones: Historical time-zone rules from the IANA database, including India's 1942–45 war time. Births in a daylight-saving gap or overlap are flagged.
Places: GeoNames, with former names such as Bombay, Madras and Calcutta mapped to the current city.

Chart conventions

Houses: Whole-sign houses by default: the rising sign is the 1st house. Placidus, Koch, Equal and Sripati can be chosen on the birth-chart form.
Ascendant near the poles: Above the Arctic and Antarctic circles the ascendant follows Swiss Ephemeris' rule that it lies in the half of the zodiac following the midheaven.
Divisional charts: D2–D60 by the classical Parashari mappings, checked on 45,000 placements against an independent implementation.
Aspects: Every graha aspects the 7th from itself; Mars also the 4th and 8th, Jupiter the 5th and 9th, Saturn the 3rd and 10th. Rahu and Ketu are given the 5th and 9th as well, as many Parashari astrologers do.
Dignity: Exaltation and debilitation are judged by sign. Rahu is treated as exalted in Taurus.
Combustion: Classical orbs from the Sun: Moon 12°, Mars 17°, Mercury 14°, Jupiter 11°, Venus 10°, Saturn 15°. The orbs are not reduced for retrograde planets.
Vimshottari dasha: Started from the Moon's nakshatra, with a 365.25-day year — the convention used by most modern software.

Yogas, doshas and matching

Yogas: Each yoga cites its classical rule. Kemadruma yoga is reported only after its classical cancellations. Budha-Aditya yoga appears in about half of all charts, so its house and Mercury's combustion matter more than its presence.
Mangal Dosha: Reckoned from the ascendant and the Moon, with cancellations. Mars is in one of the six dosha houses from the ascendant in about half of all charts. When it is formed only from the Moon it is treated as the partial form and never graded above mild. A placement counted from Venus, which some traditions also use, is mentioned but does not form the dosha.
Kundli matching: The 36-point Ashtakoot. Where classical texts disagree on half-points (Vashya and Yoni), a neutral score is used and marked approximate. Matching is also read with the Navamsa and the Mangal comparison, not the score alone.
Panchang: Sunrise is the upper limb of the Sun crossing the horizon with atmospheric refraction; tithi, nakshatra and yoga are taken at sunrise.

AI answers

The AI astrologer reads the computed chart and calls the engine for dashas, transits and divisional charts. It does not calculate positions itself, and a checker compares the placements it mentions with the chart before you see them. Interpretation is traditional and can be wrong; it is not a guarantee of events.

Astronomy

Planet positions

Computed with astronomy-engine and checked against Swiss Ephemeris: across 24 test births in 8 countries, positions agree within 11 arcseconds, and sign, nakshatra, pada, house and retrograde flags are identical.

Zodiac and ayanamsa

Sidereal zodiac with the Lahiri (Chitra Paksha) ayanamsa by default. Other ayanamsas are available in the calculators.

Rahu and Ketu

Mean node by default; Ketu is always exactly opposite Rahu. Mean and true node differ by up to about 1.5°, and our mean node sits within about 12 arcseconds of Swiss Ephemeris because of a small nutation convention.

Time zones

Historical time-zone rules from the IANA database, including India's 1942–45 war time. Births in a daylight-saving gap or overlap are flagged.

Places

GeoNames, with former names such as Bombay, Madras and Calcutta mapped to the current city.

Chart conventions

Houses

Whole-sign houses by default: the rising sign is the 1st house. Placidus, Koch, Equal and Sripati can be chosen on the birth-chart form.

Ascendant near the poles

Above the Arctic and Antarctic circles the ascendant follows Swiss Ephemeris' rule that it lies in the half of the zodiac following the midheaven.

Divisional charts

D2–D60 by the classical Parashari mappings, checked on 45,000 placements against an independent implementation.

Aspects

Every graha aspects the 7th from itself; Mars also the 4th and 8th, Jupiter the 5th and 9th, Saturn the 3rd and 10th. Rahu and Ketu are given the 5th and 9th as well, as many Parashari astrologers do.

Dignity

Exaltation and debilitation are judged by sign. Rahu is treated as exalted in Taurus.

Combustion

Classical orbs from the Sun: Moon 12°, Mars 17°, Mercury 14°, Jupiter 11°, Venus 10°, Saturn 15°. The orbs are not reduced for retrograde planets.

Vimshottari dasha

Started from the Moon's nakshatra, with a 365.25-day year — the convention used by most modern software.

Yogas, doshas and matching

Yogas

Each yoga cites its classical rule. Kemadruma yoga is reported only after its classical cancellations. Budha-Aditya yoga appears in about half of all charts, so its house and Mercury's combustion matter more than its presence.

Mangal Dosha

Reckoned from the ascendant and the Moon, with cancellations. Mars is in one of the six dosha houses from the ascendant in about half of all charts. When it is formed only from the Moon it is treated as the partial form and never graded above mild. A placement counted from Venus, which some traditions also use, is mentioned but does not form the dosha.

Kundli matching

The 36-point Ashtakoot. Where classical texts disagree on half-points (Vashya and Yoni), a neutral score is used and marked approximate. Matching is also read with the Navamsa and the Mangal comparison, not the score alone.

Panchang

Sunrise is the upper limb of the Sun crossing the horizon with atmospheric refraction; tithi, nakshatra and yoga are taken at sunrise.

AI answers