How Soulstral computes compatibility
Real astronomy, transparent scoring, nothing hand-waved. For entertainment — but the maths are genuine.
The short version
Soulstral is not a quiz. When you enter your birth details we compute your actual natal chart from astronomical ephemeris data, then score how well other birth moments form classical astrological aspects with yours. Every number you see comes from that calculation — there are no pre-written percentages and no "pick your sign" lookup tables.
1. Your natal chart
From your date, time and place of birth we calculate the positions of the Sun, Moon and planets (Mercury through Pluto) plus the lunar Node, and — when a birth time is given — your Ascendant and Midheaven. We use the tropical zodiac and Placidus houses, the same conventions used by mainstream Western astrology tools. Positions are computed with Swiss-Ephemeris-grade astronomy (the Moshier analytical model), so they match professional chart software.
2. Synastry scoring
To measure compatibility between two charts we look at synastry — the angular relationships (aspects) between one chart's planets and the other's. Around sixty planet pairings are evaluated. Each is weighted by how much it matters, which kind of aspect suits it (some connections thrive on harmony, others on productive tension), and how exact the aspect is: a contact within one degree counts for far more than one at the edge of its orb. Challenging contacts subtract from the score rather than being quietly ignored — honest friction is part of a real match.
3. Five dimensions
Every score is broken down into five human dimensions so you can see why a match works, not just a single number:
- Chemistry — attraction and spark (Venus–Mars, Ascendant, Pluto, Uranus).
- Emotional bond — feeling safe and understood (Moon contacts, Jupiter, Neptune).
- Communication — how easily conversation flows (Mercury contacts).
- Stability — the long-term glue (harmonious Saturn, Midheaven, Jupiter).
- Destiny — the "meant to be" factor (North Node, transformative Pluto).
4. Goals change the weighting
What you're looking for changes the maths. A long-term/marriage goal rewards loyalty and commitment aspects and penalises friction harder; a spark goal tolerates tension because tension can be the attraction. These aren't cosmetic labels — they re-weight the actual scoring.
5. Scores are relative and honest
Scores are expressed relative to your strongest match (your #1 = 100%). A percentage is a ranking within your own results, not a claim of absolute cosmic truth. We tell you this on purpose: the transparency is the difference between Soulstral and a horoscope generator.
Accuracy benchmark
Our aspect calculations have been checked aspect-for-aspect against astro-seek's synastry export and match it exactly. If you already use professional chart software, the underlying planetary positions will line up.
Privacy
Your birth details are processed in memory to compute your results and then discarded. Nothing you enter is written to a database or a log. See the privacy policy for the full detail.