How is a composite chart different from synastry?
Synastry compares two separate charts, while composite merges them into one midpoint relationship chart.
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Composite Chart Calculator
Free composite chart calculator. Build a midpoint relationship chart from two birth charts.
What a composite chart is
A composite chart is one chart built from the mathematical midpoints of two people's planets — the midpoint of both Suns becomes the composite Sun, and so on. The result is not either person's chart but a portrait of the relationship itself, treated as its own entity with its own signs, houses, and aspects. This calculator builds it from two sets of birth details.
Composite chart vs synastry
Synastry compares two separate charts to see how you affect each other; a composite collapses them into a single chart that describes the bond as a third thing. They answer different questions — synastry for the chemistry between you, composite for the character and purpose of the relationship you form together. Serious relationship work usually reads both side by side.
Reading the key composite points
Start with the composite Sun: its sign and house often describe what the relationship is fundamentally for. The composite Moon shows its emotional tone and what makes it feel safe; composite Venus and Mars show affection and friction; the composite Ascendant shows how the pairing comes across to the outside world. The tightest composite aspects tell you where the relationship flows and where it strains.
Questions
What does composite Sun describe?
Composite Sun often reflects the relationship’s central purpose and identity.
Can I use this for friendships too?
Yes. Composite charts can be used for any meaningful relationship type.