What is a composite chart?
A composite chart is a single chart built from the midpoints between the planets of two birth charts. Where synastry compares two separate charts, a composite merges them into one symbolic chart that represents the relationship itself, treated as a third entity.
How the composite calculator works
Enter the birth date and city for two people, and a birth time if you have it. The tool builds both charts on Swiss Ephemeris astronomy, then places each composite planet at the midpoint of the two original positions and shows the sign and degree for each.
Reading your composite chart
Read the composite Sun, Moon, and planets the way you would read a birth chart, but as a portrait of the partnership rather than a person. It describes the character and themes of a connection, not a forecast of whether it will last.
Composite vs synastry
Synastry studies the aspects between two charts; the composite condenses both into one relationship chart. Many astrologers use them together. For the aspect view, try the synastry calculator, and see the AstrologyWiki wiki for a deeper written guide.