How Navagraha Calculates
Our ephemeris, conventions, classical rules and accuracy checks
Updated
Every chart, dasha, Panchang and compatibility score in Navagraha comes from published astronomical data and classical Jyotish rules, applied the same way every time. This page sets out exactly which conventions we use, so you can compare our results with any other software or astrologer.
Planetary positions
- Ephemeris: the app computes positions with the Swiss Ephemeris (Astrodienst), the high-precision ephemeris used by most professional astrology software, accurate to well under an arc-second for the planets in historical and modern dates.
- Zodiac: sidereal, using the Lahiri (Chitrapaksha) ayanamsa — the standard adopted by the Indian government's Calendar Reform Committee and the default in most Indian software.
- Rahu and Ketu: the app uses the true node. Some software (and many printed almanacs) use the mean node; the two differ by up to about 1.7°, which can occasionally change a nakshatra pada.
- Houses: whole-sign houses from the Lagna (ascendant), the classical Parashari approach. The Lagna degree is computed from local sidereal time for your exact birth place.
- Time zones: historical time-zone and daylight-saving rules from the IANA database are applied to your birth time, which matters for births in India before 1955 and abroad.
Classical rules
- Charts: D1 (Rashi) and the divisional charts (Navamsa D9 and the Shodashavarga) follow Brihat Parashara Hora Shastra (BPHS).
- Vimshottari dasha: 120-year cycle starting from the Moon's nakshatra lord, with the balance at birth from the Moon's position in its nakshatra and a 365.25-day year.
- Kundli matching: Ashtakoot (36 gunas) with the standard koota tables (as in Muhurta Chintamani), directional Varna, Tara and Gana scoring, and the common Nadi and Bhakoot dosha exceptions.
- Doshas: Mangal dosha from Lagna, Moon and Venus with the usual cancellations; Kaal Sarp in full and partial forms; Sade Sati and Dhaiya from Saturn's transit relative to your Moon sign.
- Panchang and muhurat: the day runs from local sunrise (upper limb, standard refraction); Rahu Kaal, Yamaganda and Gulika divide daylight into eight parts; tithi, nakshatra, yoga and karana end times are solved to the minute.
How we check accuracy
The engine is tested against reference charts before every release: planet signs, nakshatras and padas for well-known public charts (45 of 45 planets and all ascendants match AstroSage), Ashtakoot totals for worked examples, Panchang timings against published almanacs (within 1–3 minutes) and Saturn, Jupiter and Rahu ingress dates against published ephemerides. The free calculators and the developer API on this site use a lightweight JavaScript engine that is tested against the same references.
The AI Pandit
Readings in the app are written by an AI model that is given your computed chart — positions, dashas, strengths, yogas and current transits — and instructed to stay within classical interpretation, avoid fear-based predictions and never give medical, legal or financial advice. The calculations are deterministic; the interpretation is AI-generated, so treat it as guidance for reflection rather than certainty. You can report any reading that seems wrong or harmful from inside the app.
Limits
- A chart is only as accurate as the birth time. A few minutes can change the Lagna, houses and divisional charts; the Moon sign can change on days when the Moon changes sign.
- Astrology traditions differ (ayanamsa, node, house system, dosha rules). Where they do, we follow the conventions above and say so.
- Navagraha is for informational and reflective purposes and is not a substitute for professional advice.
Frequently asked questions
Which ayanamsa does Navagraha use?
Navagraha uses the Lahiri (Chitrapaksha) ayanamsa, the standard adopted by the Indian government and used by most Indian astrology software. It is applied to Swiss Ephemeris positions to give sidereal longitudes for every planet and the ascendant.
Why does my chart differ slightly from another website?
Small differences usually come from the ayanamsa (Lahiri, Raman, KP), the lunar node (true or mean Rahu), the house system or the birth time zone. Navagraha uses Lahiri, the true node and whole-sign houses, and applies historical time-zone rules to your birth time.
Is Navagraha accurate?
Planetary positions come from the Swiss Ephemeris and are accurate to a fraction of an arc-second. The engine is tested against public reference charts and published almanacs before each release. Personal accuracy depends most on having the correct birth time.
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Open Navagraha →Navagraha provides Vedic astrology for informational and reflective purposes only; it is not a substitute for professional advice.