Synastry and composite
Synastry Chart Calculator
Enter the birth details of two people. We calculate the links between their charts, where one person’s planets fall in the other’s houses, and both the composite and the Davison relationship chart.
Synastry and composite
The couple’s charts
Your birth chart with its houses is inside the wheel, the other person’s chart around it. The lines are the strongest aspects between one person’s planets and the other’s.
Links between the charts
The other person’s planets in your houses
Your planets in the other person’s houses
The composite is a single chart of the relationship: each planet sits at the midpoint of the shorter arc between the two people’s positions of that planet. It is not the sky of any real moment, so it has no retrograde planets.
Planets
Houses
Aspects
Midpoint method after Robert Hand (Planets in Composite, 1975). Houses are the midpoints of the Placidus cusps, oriented by the MC midpoint.
The Davison chart is the real sky at the moment exactly halfway between both births, above the place halfway between the birthplaces.
Planets
Houses
Aspects
Ronald Davison’s method (Synastry, 1977): the midpoint in time of both births and the mean latitude, with longitude taken at the midpoint of the shorter arc. Placidus houses.
Three ways to look at a relationship
Synastry
Compares two birth charts side by side. Aspects between the planets show where two people meet naturally and where they rub against each other; planets in the other person’s houses show which area of life one person stirs in the other.
Composite
Turns two charts into one, the chart of the relationship itself. It is read like a birth chart, except that it describes what the couple creates together rather than a person.
Davison chart
Another chart of the relationship, but unlike the composite it is the real sky of one moment and place, so its planets stand in real positions to each other.