Free Synastry Compatibility Calculator
A sun-sign compatibility chart treats everyone born in the same month the same way. AiRA instead uses synastry — comparing your actual birth chart against theirs, calculated from both people's real birth date, time, and place.
What you get
- Compares your birth chart against theirs planet-by-planet (synastry) — not just a sun-sign match
- Calculated from both people's real planetary positions via Swiss Ephemeris
- Shows where you naturally click and where the relationship needs more care
- Works for romantic relationships, family, or coworkers
What synastry actually compares
Synastry overlays one person's birth chart onto the other's and studies how their planets interact. The moon-to-moon comparison speaks to emotional compatibility, Venus and Mars placements speak to attraction and affection styles, and Saturn or Mercury contacts often speak to long-term stability and communication. AiRA runs this comparison from both people's real birth data instead of reducing it to a single sun-sign lookup.
Does a low compatibility score mean it won't work?
Synastry describes where two charts meet easily and where they grind — it does not rank relationships as good or doomed. Plenty of lasting pairs score low on one dimension and simply learned the workaround; plenty of high scores went nowhere because nobody showed up for it. What the comparison is genuinely useful for is naming the friction precisely: knowing that the grind sits in communication rather than trust changes what you actually do about it. The score is a description of the terrain, not a prediction of who reaches the other side.
Check your compatibility with someone, calculated from both real birth charts.
Check compatibility freeFrequently asked questions
How is AiRA's compatibility check different from a typical zodiac sign match?
AiRA uses synastry — comparing your planetary positions against theirs one by one — instead of a generic sun-sign compatibility table.
What information do I need to check compatibility?
Both people's birth date, time, and place. More precise birth data gives a more detailed result.
Can this be used for relationships other than romantic ones?
Yes. Synastry compares the relationship between any two people — romantic partners, family, or coworkers.
What does synastry actually look at, beyond sun signs?
Synastry considers both people's key planet placements — the moon (emotions), Venus and Mars (attraction and how affection is expressed) — plus the aspects (angles) formed between one person's planets and the other's. It's never just a sun-sign comparison.
Does high compatibility guarantee a smooth relationship?
No. Synastry shows astrological tendencies and points worth paying attention to, not a guaranteed outcome. A real relationship still depends mainly on communication and effort from both people.
Curious how it's calculated? See how AiRA works, or check today's horoscope. Also read the disclaimer on the system's limits.