Tool 15 / Astrology
Birth Chart Calculator
Calculate planetary sidereal positions, your Vedic Moon sign (Rashi) and rising sign (Lagna) from your birth date, time and coordinates. Every method and limitation is documented.
Manual
04 stepsHow to use it
- 01Enter the birth date and, for Lagna, the exact local birth time.
- 02Set the UTC offset that was in force at the birthplace.
- 03Enter latitude and longitude, or pick a preset city to fill them.
- 04Generate the chart to see planetary sidereal positions, Rashi and Lagna.
Example
What it looks like
- Input
- 14 March 1990, 09:20 IST (UTC+5:30), 28.6139° N, 77.2090° E
- Output
- Tropical Sun in Pisces (Western), sidereal Sun in Aquarius, plus Moon Rashi, Lagna and a nine-planet position table
Positions are computed with an astronomy library; the house system shown is whole-sign.
Method
How it works
Planetary positions are calculated with the open-source astronomy-engine library, using your birth date converted to UTC. Geocentric ecliptic longitudes are converted from the tropical to the sidereal zodiac with a Lahiri ayanamsa approximation, which is close to, but not identical with, official ephemerides.
Lagna (the ascendant) is found by solving for the ecliptic degree that sits exactly on the eastern horizon at your birth moment and coordinates. That is why an exact time matters: the ascendant moves roughly one degree every four minutes.
Rashi is your Moon sign in the sidereal zodiac, not your Western Sun sign. Rahu and Ketu are calculated with the mean lunar node formula, which can differ by up to about 1.5° from true-node ephemerides. The whole-sign house system is used, so house results will differ from systems like Placidus or Sripati.
FAQ
Before you ask
Specific to birth chart calculator, including limits and privacy.
Why do the Vedic and Western signs differ?
The two systems use different reference points. The tropical zodiac starts at the vernal equinox, while the sidereal zodiac is measured against the fixed stars, currently about 24° apart.
How exact is the calculation?
Planetary longitudes come from a modern astronomical ephemeris and are reliable for chart display to a small fraction of a degree. The Lahiri ayanamsa here is an approximation, and mean node values differ slightly from true-node tables.
What if I do not know my birth time?
You can still see the Sun and outer-planet signs, but the ascendant and house placements depend on time. Without a time they are not shown rather than guessed.
Is my birth data stored?
No. The calculation happens when you press the button and the result is returned to the page. Birth details are not saved, logged or attached to an account.
Privacy
Date, time and coordinates are sent to our calculation endpoint only to compute the chart for that request. They are not written to the database or logs.
Read the privacy policy for data retention, analytics and contact details.
Limits
Astronomical positions are computed data; their astrological interpretation is not scientifically validated. Use this for study and curiosity, not for medical, financial or life decisions.
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