How We Calculate Your Vedic Birth Chart
Full technical transparency. No black boxes. If you want to verify our results, everything here links to primary sources.
Accuracy depends primarily on birth time. For precise Ascendant calculation, birth time within ±10 minutes is ideal. If you don't know your exact time, planetary positions will still be highly accurate.
7-Step Calculation Pipeline
Geographic Coordinates
Your birth place is converted to precise latitude/longitude using OpenStreetMap Nominatim geocoding. Time zone is resolved from coordinates, not just city name — this eliminates DST errors.
Julian Day Number
Your birth date and time are converted to a Julian Day Number — the universal astronomical timestamp. This accounts for all calendar reforms including the Gregorian/Julian switch.
Swiss Ephemeris Calculation
Planetary positions are computed using the Swiss Ephemeris library — the same engine used by professional astronomers. Accuracy is within 0.001 arc-seconds over a 10,000-year range.
Lahiri Ayanamsa Applied
The tropical zodiac positions are converted to the sidereal zodiac using Lahiri (Chitrapaksha) Ayanamsa — the standard adopted by the Indian government and recommended by the Rashtriya Panchang.
Ascendant & House System
The Ascendant (Lagna) is calculated from the exact moment and location, then the 12 houses are set using the whole-sign system — the classical Parashari house division used in traditional Jyotish.
Vimshottari Dasha
The Dasha cycle is computed from the Moon's Nakshatra position at birth. The remaining balance of the birth Dasha is calculated to the day, with all sub-periods (Antardasha) computed accurately.
AI Interpretation
Planetary positions, house lords, aspects, and Dasha sequences are sent to GPT-4o with a structured prompt grounded in classical Parashari Jyotish texts. Output is reviewed for accuracy, specificity, and freedom from generic statements.
Ayanamsa — Why We Use Lahiri
Ayanamsa is the difference between the tropical and sidereal zodiacs. Different schools use different values — here's where ours fits.
| Ayanamsa System | Value (2024) | Notes |
|---|---|---|
| Lahiri (Chitrapaksha)WE USE THIS | ~24.13° | Government standard · Most widely used in India |
| Raman | ~22.46° | Used by some traditional schools |
| Krishnamurti (KP) | ~23.86° | KP astrology system |
| Fagan/Bradley | ~24.77° | Western sidereal — not used in Jyotish |
Our Accuracy Standard
Every planetary position we display is cross-verified against Swiss Ephemeris. If you find a discrepancy, email us with your chart data and we will investigate within 24 hours.