Find your supernova
Do your charts align?
Two birth charts, one honest read. Computed in your browser, no account needed.
The method
How compatibility works
Sun
The Sun is core identity, how each of you moves through the world when nobody's watching. Comparing Sun signs shows how you vibe on a personal level: whether your basic temperaments run parallel or pull in different directions.
Moon
The Moon is emotional instinct, the reactions that happen before you think. Comparing Moon signs shows how you align emotionally: whether you process feelings on a similar rhythm or need different things to feel safe.
Rising
The Rising sign (the sign on the horizon at the moment of birth) is the first impression, the mask before anyone gets close. Comparing Rising signs shows how you show up together, but it needs an exact birth time to be honest.
Definition
What is synastry?
Synastry lays one birth chart over another and measures the angles, called aspects, between every planet in one chart and every planet in the other.
Some angles are supportive (a trine, a sextile), some create friction (a square, an opposition), and some are simply intense either way (a conjunction). This calculator runs the comparison on real ecliptic longitudes, then turns it into per-dimension scores and a list of the tightest contacts between your two charts.
FAQ
Questions
Is this accurate without birth time?
Sun and Moon signs barely move in a day, so those stay accurate without an exact time. Rising sign needs the real minute, so we leave it out entirely rather than guess. Check the box for unknown birth time and the rest of the reading still holds.
Is compatibility just sun signs?
No. Sun-sign columns are a simplification. A real synastry read compares the Sun, Moon, Mercury, Venus, Mars, and the outer planets across both charts, the angles between them (called aspects) carry more information than either sun sign alone.
Can I check friends and coworkers, not just partners?
Yes. Synastry is just the comparison of two charts, it works the same way for a partner, a friend, a sibling, or a coworker. The axes read differently depending on the relationship, but the math doesn't change.
Does a hard aspect mean we're doomed?
No. A square or opposition means friction exists somewhere specific, not that the relationship fails. Tension in a chart is information, not a verdict, plenty of long relationships run on a few hard aspects handled well.
How is the overall score calculated?
It's computed from the geometric angles between both charts' planets, no keywords or fortune telling involved. Supportive angles (trines, sextiles) add to a dimension's score, tense ones (squares, oppositions) subtract from it, and the total settles around a neutral midpoint when there's little contact at all.
Is my data stored?
The chart itself is computed entirely in your browser and never leaves it. We only store an email address if you choose to enter one for a copy of the reading.