Our Calculation Method

Planetary positions

Every kundali is built in our own calculation engine — not by renting outside software. The Sun and planets come from the VSOP87 theory and the Moon from a shortened series of the ELP-2000/82 theory — both recognised mathematical models in astronomy. Rahu and Ketu are taken from the mean lunar node — as the printed planetary table of the Bishuddha Siddhanta Panjika also does (1 December 2026: printed Aquarius 0°14′49″, ours 0°14′50″).

The panjika's planetary table is built from NASA JPL's DE441 positions. Every day of the table is checked against our engine, and several dates directly against JPL Horizons, by automated tests.

The seven planets of the kundali engine are compared with Swiss Ephemeris on 401 dates from 1950 to 2050: Venus, Mars, Jupiter and Saturn agree within 6 arcseconds, the Sun within 8, the Moon within 26 and Mercury within 75 arcseconds — the sign and nakshatra are the same on every date. The ascendant (lagna) agrees within 2 arcseconds in 401 charts across ten cities. The comparison runs again whenever the engine changes.

Ayanamsha

Sidereal calculation uses the Lahiri (Chitrapaksha) ayanamsa — the one adopted in the Government of India's Rashtriya Panchang. Values are taken from the printed monthly table of the Bishuddha Siddhanta Panjika; for years without a printed value, the Lahiri formula is used, which agrees with the printed values within 0.3 arcseconds. Every calculation on the site and in the app comes from this one source.

Panjika and festivals

Tithi, nakshatra, yoga, karana and festival dates and times are calculated by the Bishuddha Siddhanta Panjika and checked to the minute against the printed panjika — any difference is within one minute. Example: Kojagari Lakshmi Puja on 26 October 2026; Purnima begins at 11:57 am on 25 October — the same in the printed panjika and in our calculation.

The Hindi and English panchang are not translations of the Bengali one — they follow north-Indian practice: the day's tithi is taken at sunrise in the reader's own city, sunrise is the Sun's upper limb with refraction (the drik convention; disc centre on request), month names are Purnimanta or Amanta as the reader chooses, and Amrit Kaal comes from the amrita-ghati table of Prasna Marga (B. V. Raman's edition). The Bengali panjika keeps the printed Bishuddha Siddhanta convention — Kolkata sunrise, centre of the Sun's disc.

The Bishuddha Siddhanta Panjika itself states that its calculation agrees with the method of the Rashtriya Panchang published by the Government of India, and that this method was recognised by Meghnad Saha and Nirmal Chandra Lahiri. According to the panjika's own acknowledgement, Anandabazar Patrika, Bartaman, Dainik Statesman, Khabor 365 Din, Sangbad Pratidin and Aajkaal print the daily Bengali date according to this panjika.

Every observance and every great person's birth anniversary respects its own year — no one's birthday is shown in a panjika for a year before they were born.

Dasha

Vimshottari mahadasha, antardasha and pratyantardasha are calculated from the Moon's nakshatra position at birth. Every antardasha period is verified against all 81 cells of the table in Harihar Majumdar's book on applied astrology.

Horoscope matching

Ashtakoota guna matching follows the printed Yotaka-chakra and the rules of the classical texts. Where two sources disagree, one path is chosen by the astrologer's scriptural ruling, and the report states the reason openly.

Gulika, Mandi and Pranapada

Gulika, Mandi and Pranapada lagnas are calculated by the rules of Harihar Majumdar's text. For Gulika and Pranapada the text's own worked examples are run and matched; for Mandi the numbers are matched against the text's table. Sunrise is taken for the birthplace itself.

Planetary strength and weakness

The rules of the divisional charts — hora, saptamsha, navamsha and dwadashamsha — were written out independently from Harihar Majumdar's book on predictive astrology and checked against our engine at 360,000 points of the zodiac; not a single mismatch.

A combust planet is treated as weak within the limits given in the same book: Jupiter 11°, Saturn 15°, Mars 17°, Moon 12°, Venus 10° (8° when retrograde), Mercury 14° (12° when retrograde). As the book says, Venus and Saturn are not wholly powerless even when combust.

A planet in an enemy's sign is judged from the printed table of natural friendships — the Moon, for example, has no natural enemies, so the Moon is never in an enemy's sign.

A retrograde planet is not weak but strong — in Parashara's Shadbala a retrograde planet receives full motional strength (cheshta bala), as B. V. Raman also explains.

Shadbala is computed by the method of B. V. Raman's Graha and Bhava Balas — with saptavargaja strength, the nine parts of kala bala, cheshta and drik bala. The book's own example horoscope was run through our engine and all 49 of its figures match; the largest difference is 0.11 shashtiamsa. A planet whose total strength equals or exceeds its required minimum is strong.

Three languages, one calculation

Bengali, Hindi and English — the same engine gives the same result in all three languages; only the text is translated. The website and the Android app both use this same calculation.

The role of AI

AI does not do the calculations. Planetary positions, tithi, dasha, guna matching and strength are all computed by fixed formulas in our engine and checked by the tests above. The engine's code was written with the help of AI assistants; every rule is set by the astrologer's judgement, and every change is published only after passing the tests.

The daily rashifal is written by a program — from that day's transits, keeping the key words of the transit results in the Bishuddha Siddhanta Panjika. The sentences were drafted with AI help, but whether a result is favourable or not is decided by the panjika's rule.

The detailed text of the premium report is written by Google's Gemini AI from our engine's calculations — AI does not decide planetary positions or dashas itself. Dr. Prodyut Acharya reads every premium report himself, and corrects it where needed, before it is delivered.

Scriptural supervision

Calculation rules are set from printed texts and the panjika; where the texts differ or are unclear, Dr. Prodyut Acharya (PhD, Vedic Jyotish) decides. A rule with no source in the texts is not added by guesswork. Not every sentence of a prediction is quoted from a text — much of it is explanatory writing, some of it produced with AI help (see above).

Limits we state openly

A kundali is only as accurate as the birth time — on average the ascendant moves about one degree every four minutes, so even a few minutes' error can change its degree.

Our reports are astrological guidance; they are not a substitute for professional medical, legal or financial advice.