Birth Chart Compatibility Calculator
Sun sign horoscopes only tell you so much about a relationship. Real astrological compatibility comes from comparing two whole birth charts - your planets against theirs - to see where you click and where you'll feel the friction. Enter both sets of birth details below and the calculator will map your match in under a minute.
Person 1
Person 2
Enter birth date and place for both people to continue. Birth time is optional.
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Calculate Your Compatibility
Enter both birth details below to generate your compatibility chart. For each person you'll add three things: birth date, birth time, and birth place. Then the calculator lines up the two charts side by side and shows where your placements meet.
The more precise your details, the sharper the read. Birth times in particular matter, because they set the Moon, the rising sign, and the houses - all of which shape how two people actually fit together day to day. If one of you doesn't know an exact time, you can still run the comparison; just treat the Moon and house contacts as approximate.
Once both charts load, you'll see your strongest connections and your trickiest tensions, ready to read.
How the Compatibility Calculator Works
The calculator builds a full birth chart for each person, then overlays them to find the aspects between your planets - the angles that astrologers read as the chemistry of a relationship. This planet-to-planet comparison is the heart of synastry.
Here's what you give it and what you get back:
- Two sets of birth details. Date, time, and place for each person, so the calculator can plot both charts accurately.
- The key contacts between you. The calculator focuses on the placements that carry the most weight in a relationship - your Suns, Moons, Venus, and Mars - plus the aspects they form.
- A read on where you align and where you clash. Harmonious aspects point to where things flow easily; tense ones flag where you'll need to work at it.
No pairing is all green lights or all red flags. The calculator gives you the raw contacts; the meaning comes from reading them together.
What Birth Chart Compatibility Looks At
Birth chart compatibility goes well beyond whether your star signs are "meant to be." A few placements do most of the heavy lifting:
- The Suns - your core selves and whether your basic styles support or grate on each other.
- The Moons - your emotional needs and how safe you feel with one another.
- Venus and Mars - attraction, affection, and desire, and how the spark plays out.
- The aspects between them - the angles that turn two separate charts into a relationship with its own dynamic.
This page is built to run the comparison. If you want the full picture of how compatibility works across the whole chart, start with our birth chart compatibility guide, or read up on the technique behind it in our synastry guide.