Every online astrology calculator on Sigastra

How every online astrology calculator here fits together

Every tool above starts the same way. Give it a date, a time and a place, and the ephemeris gives the position of every planet as seen from that place, using the time zone rules that applied there that year. Each tool then reads those positions in its own way. If a term is new to you, the Learn guides cover the elements, modalities, houses and aspects.

The three layers, from slowest to fastest

The birth chart is the still photo, and it never changes. Solar and lunar returns, along with progressions, move that photo forward in time and compare it with the sky now. Horoscopes are the fast layer, from the daily forecast that follows the Moon to the yearly one that follows Jupiter and Saturn. Think of them as different zoom levels on the same sky.

Which of these needs your birth time

The Ascendant moves about a degree every four minutes, so anything built on it, including the Rising sign calculator, the houses of a natal chart and every solar or lunar return, is only as good as the birth time you enter. Your Sun sign, planetary positions and sign compatibility need only your birth date, and so does your Moon sign on most days. When a time is missing, we tell you which parts of a reading still hold.

Free or Plus?

Every position is calculated the same way whether you pay or not. The full birth chart, the daily horoscope and the compatibility overview are free, with no account needed. Sigastra Plus adds the written interpretations: synastry and composite readings, the return charts and the full house-by-house natal reading. The badge next to each tool above shows which is which.