Sidereal Vedic chart using Lahiri Ayanamsha and whole-sign houses. Here's the detail behind that one line.
Solar and lunar positions use the Meeus solar/lunar series; the other planets use Standish J2000 planetary elements. In practice this is accurate to about 1 arc-minute for the Sun and Moon, and a few arc-minutes for the other planets — genuinely good for everyday chart reading, dashas, yogas, and most Muhurta work.
It is not (yet) precise enough for birth-time rectification or the most exacting, minute-level Muhurta timing, where a few arc-minutes of drift can matter. We're upfront about this rather than overselling the tool's precision — a future upgrade to Swiss-Ephemeris-grade precision is on our roadmap for exactly those use cases.
We use Lahiri (Chitrapaksha) ayanamsha, the standard reference point for modern Vedic astrology, to convert tropical positions to sidereal.
Rahu and Ketu are calculated using the mean node by default.
Whole-sign houses (Bhava) — the sign containing the Ascendant is the whole 1st house, the next sign is the whole 2nd house, and so on. No house interceptions.
Your birth time is converted to UTC using your birth city's real historical timezone rules — including daylight saving, resolved for your exact birth date, not a single fixed offset. This matters: a city's UTC offset can differ by an hour or more between summer and winter, and using the wrong one shifts your Ascendant and every house. If you entered your city by searching for it, this is handled automatically; if you entered raw latitude/longitude and a manual UTC offset instead, that value is not automatically DST-corrected, and you're responsible for entering the correct historical offset for your exact birth date.
Astrocartography, Varshaphal (solar return charts), Prashna (horary astrology), birth-time rectification, and the highest-precision Muhurta timing all wait on a future ephemeris upgrade — we'd rather ship these once they can be genuinely precise than ship an approximate version now.
See our FAQ, or contact us directly.