One chart for two people
A composite chart treats a relationship as something with a life of its own. For each planet, it takes the two people's positions and finds the point halfway between them. If one person's Sun is at 10° Aries and the other's at 20° Gemini, the composite Sun sits at 15° Taurus, halfway along the shorter arc. Repeat that for every planet and point and you get a new chart that belongs to neither person and describes the partnership. The technique was popularized by the astrologer Robert Hand in the 1970s and is now one of the two standard ways to look at a relationship, alongside synastry.
Composites work for any close relationship: couples, friends, family members, business partners. The calculator doesn't give a compatibility score, because no single number captures a relationship; it shows the chart and what astrologers look at first.
What to read first
- The composite Sun: what the relationship is for, its core purpose and identity. Its house shows the area of life the partnership centers on: the 5th house for romance and fun, the 10th for a shared public life or work, the 4th for home and family.
- The composite Moon: what the relationship needs to feel safe and how it handles feelings.
- The composite Venus: how affection is shown and what you enjoy together.
- The composite Ascendant: how you come across as a couple.
- The aspects: flowing aspects (trines and sextiles) are read as ease, and challenging ones (squares and oppositions) as friction that asks for work, the relationship's own strengths and growing pains.
How the chart is built
Planets and points use the midpoint on the shorter arc between the two positions. The Midheaven does the same. The Ascendant and houses are then derived from the composite Midheaven at a chosen latitude, the approach Robert Hand recommended, because averaging two Ascendants can produce an Ascendant and Midheaven that could never occur together anywhere on Earth. If you enter where you live together, that latitude is used; otherwise, the latitude halfway between your two birthplaces. The house system follows Chart settings (Placidus by default).
One known quirk of every midpoint composite is worth knowing about. Because each midpoint is taken separately, planets that always travel close to the Sun, like Mercury and Venus, can occasionally land on the opposite side of the chart from the composite Sun. That's a property of the method, not an error.
Composite, synastry or Davison?
| Method | What it is | Best for |
|---|---|---|
| Synastry | One chart overlaid on the other | How two people affect each other |
| Composite | Midpoints of both charts | The relationship as a thing in itself |
| Davison | The sky at the midpoint in time and space | A real moment that stands for the relationship |
This site has the first two: see the synastry chart for every contact between your charts and the house overlays.
Where would the relationship thrive?
Astrocartography can answer that for two people. Add your partner on the map and tick "Rank for both of us" in where should I live: cities then rank by how both charts' lines treat them. To start with the basics, compare your Venus signs or read about astrocartography lines for love.