Compare
Tropical vs sidereal astrology
The short answer: They’re two rulers for the same planets. The tropical zodiac is fixed to the seasons, with 0° Aries at the March equinox; the sidereal zodiac is fixed to the stars. The two have drifted apart, so sidereal positions currently sit roughly 24° earlier and many placements move back one sign. Most Western astrology uses the tropical zodiac; Vedic astrology (Jyotish) uses the sidereal.
Tropical zodiac and Sidereal zodiac, side by side
| Tropical zodiac | Sidereal zodiac | |
|---|---|---|
| Reference point | The March equinox: 0° Aries is the Sun’s position on that day | A fixed point among the stars, set by the chosen ayanamsa |
| Tied to | The seasons | The constellations behind the signs |
| Offset | None: it is the reference | Currently roughly 24°, growing by about one degree every 72 years |
| Effect on signs | The signs most Western horoscopes give | Often one sign earlier; a planet late in a sign may keep it |
| Aspects | Measured between planets | Identical: every position shifts by the same amount |
| Variants | One standard definition | Several ayanamsas; Lahiri is widely used, others include Fagan–Bradley and Krishnamurti |
| Used by | Most Western astrology | Vedic astrology (Jyotish), and Western sidereal astrologers |
| In Soul Cartography | The free calculator, and one of the views in your Manual | A view in your Manual, using the Lahiri ayanamsa |
which zodiac is “correct”. Each one is consistent, with its own tradition behind it, and we show you both instead of picking a side.
What each one reads
Tropical zodiac
Signs measured from the March equinox, so the zodiac stays in step with the seasons.
It names: Sun, Moon and rising sign, Planets by sign and degree, Houses and angles.
Sidereal zodiac
Signs measured against the background stars, by subtracting an offset called the ayanamsa from each tropical position.
It names: Sun, Moon and rising sign, Planets by sign and degree, Houses and angles.
Calculate each, free
Tropical birth chart
The free calculator uses the tropical zodiac: every planet by sign, degree and house.
Start from your birth chart
The free calculator is tropical; subtracting roughly 24° gives an approximate sidereal position. Your Manual shows the sidereal view in full.
Common questions
Why is my sidereal Sun sign different?
The sidereal zodiac starts roughly 24° earlier, so a planet in about the first 24° of a tropical sign falls in the previous sidereal sign. One in the last few degrees keeps its sign.
Which ayanamsa does Soul Cartography use?
Lahiri, the one most commonly used in Vedic astrology. Other ayanamsas differ from it by around a degree, which can matter for a planet near the edge of a sign.
Is one zodiac more accurate?
They measure from different references, so neither is a correction of the other. The tropical zodiac follows the seasons; the sidereal follows the stars.
Does the sidereal view change my Human Design or Gene Keys?
Standard Human Design and Gene Keys charts use tropical positions. Soul Cartography’s sidereal comparisons of them are its own extension, and are labelled.