Free Sidereal Astrology Calculator
Enter your birth details to generate your complete sidereal chart. Uses the Lahiri (Chitrapaksha) ayanamsa, the standard used by most English-language sidereal calculators.
What is a sidereal astrology chart?
A sidereal natal chart places the planets against the sidereal zodiac, a 12-sign system anchored to the fixed stars rather than the equinoxes. Because Earth's axis wobbles slowly (a phenomenon called axial precession), the two zodiacs have drifted apart by about 24 degrees over two millennia. This gap is called the ayanamsa. Your sidereal Sun, Moon, and rising sign are typically one sign earlier than your tropical equivalents.
This calculator uses the Lahiri (Chitrapaksha) ayanamsa, the standard adopted by the Indian government in 1955 and the most widely used reference for English-language sidereal calculators. The exact ayanamsa value applied to your chart is displayed in the results so you can verify it against any other Lahiri-based tool.
Planetary positions are computed to arc-second precision using NASA's ANISE toolkit and JPL planetary ephemerides. The ayanamsa is then applied client-side to shift all positions from tropical to sidereal coordinates. Aspects between planets are not shifted because they measure relative angles, which are unchanged by the zodiac reference frame.
What changes in your sidereal chart?
For most people, the Sun shifts one sign back. Someone with a tropical Sun at 5° Taurus has a sidereal Sun at roughly 11° Aries (after subtracting the ~24° ayanamsa). People born in the first 24 days of a tropical sign often remain in the same sidereal sign; people born in the last week of a tropical sign are in the classic "cusp zone" most likely to shift.
The rising sign is the most sensitive placement because it changes every two hours. Even a small ayanamsa shift can move the Ascendant into the previous sign, which changes the entire house structure and the chart ruler. If your chart was computed using the tropical zodiac, the sidereal Ascendant is the placement most likely to surprise you.
Aspects between planets are the same in both systems. A Sun-Moon trine in the tropical chart is also a Sun-Moon trine in the sidereal chart. The angles between bodies do not change; only the zodiac backdrop against which they are described changes.
To understand the history and debate around sidereal versus tropical astrology, see the sidereal astrology guide. For approximate sidereal Sun sign dates by sign, see the sidereal Sun sign dates hub.
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Frequently Asked Questions
What is the difference between a sidereal and tropical chart?
A tropical chart anchors 0° Aries to the March equinox. A sidereal chart anchors 0° Aries to the fixed stars. Because Earth's axis wobbles over a 26,000-year cycle, the two systems have drifted roughly 24 degrees apart. Most people's sidereal Sun is one sign earlier than their tropical Sun.
What ayanamsa does this calculator use?
This calculator uses the Lahiri (Chitrapaksha) ayanamsa, IAE 1985 standard. It is the official ayanamsa of the Indian government and the most widely used reference for English-language sidereal calculators. The exact ayanamsa value applied to your chart is displayed in the results.
Why is my sidereal sign different from my tropical sign?
Because of axial precession, the tropical and sidereal zodiacs have drifted about 24 degrees apart over two millennia. The Sun moves roughly 1 degree per day, so this 24-degree gap means your sidereal Sun sign typically starts about 24 days after the tropical equivalent. People born in the last week of a tropical sign are most likely to shift.
Are aspects the same in sidereal and tropical charts?
Yes. Aspects measure the angular distance between two planets, which is the same regardless of which zodiac system you use. A trine in your tropical chart is also a trine in your sidereal chart.
Is sidereal astrology the same as Vedic astrology?
Not exactly. Vedic (Jyotish) astrology uses the sidereal zodiac, typically with the Lahiri ayanamsa, but it also includes its own interpretive framework (dashas, nakshatras, yogas) that is distinct from Western astrology. This calculator produces Lahiri sidereal positions, which are consistent with Jyotish chart positions, but does not apply Jyotish interpretive techniques.
Your chart has been active your whole life. Replay shows how.
Every placement in your chart has been activated at different intensity across different chapters. Replay maps how your chart has expressed over time and which patterns are building next.