How RishiAstro calculates

Where the planetary positions come from

Planets are computed from VSOP87, the semi-analytic planetary theory published by the Bureau des Longitudes, and the Moon from the ELP lunar theory. Both are evaluated inside our own engine on our servers.

There is no third-party astrology API in the path and no lookup table of precomputed charts. That is why an unusual birth date — a leap day, a pre-1900 year, a high-latitude birthplace — returns the same quality of result as a common one.

Sidereal zodiac and ayanamsa

Vedic astrology is sidereal: it measures from the fixed stars rather than the equinox, and the offset between the two is the ayanamsa. Which value you use shifts every position, so it is the single largest source of disagreement between astrology sites.

• Lahiri (Chitrapaksha)— default. The standard for Indian Vedic astrology and the basis of the Indian government’s Rashtriya Panchang.
• Raman, KP and True Chitra — selectable alternatives for readers who follow those schools.

Whichever you choose is applied consistently across the chart, divisional charts, dashas and yogas, so a reading is never a mixture of two systems.

Houses, charts and dashas

Houses are counted whole-sign from the Lagna — the classical Vedic convention, and the one the dosha and yoga logic assumes. Charts are rendered in both North Indian (diamond) and South Indian (square) styles from the same underlying data, along with the D9 Navamsa. Vimshottari, Yogini and Char dasha timelines are computed from the Moon’s exact nakshatra position at birth.

How the matchmaking output is checked

Ashtakoot Gun Milan output has been cross-checked against AstroSage, and agrees on roughly 93% of test cases.

The residual difference is not arithmetic. It comes from koota conventions that genuinely differ between traditions — Nadi and Bhakoot dosha in particular are cancelled under conditions some schools accept and others do not, and the bride/groom order changes the directional kootas (Varna, Gana). When two sites disagree on a 36-guna score, this is almost always why.

What this is not

The astronomy is deterministic and reproducible; the interpretation built on it is a traditional belief system, not a scientific claim. Readings here are for guidance and reflection, and are not a substitute for professional medical, legal, financial or psychological advice. See our Terms of Service.