What is a Composite Chart?

Synastry compares two charts; a composite chart mathematically combines them into a third, entirely new chart. That chart belongs neither to A nor to B — it belongs to the relationship itself.

How it is calculated

For each planet, the midpoint between its positions in the two charts is taken. If A's Venus is at 10° Aries and B's Venus is at 20° Aries, the composite Venus falls at 15° Aries. The same operation is repeated for every planet, for the Ascendant and for the house cusps.

What emerges is a single arrangement of planets, signs and houses that was never actually lived by anyone, yet is mathematically consistent — as though the relationship had a birth chart of its own.

How the "personality of a relationship" is read In a composite chart the Sun is taken to describe the relationship's core purpose and identity; the Moon, its emotional need; the 7th house, how the relationship appears to the outside world. The chart looks for an answer to "what kind of being are we when we are together" — not "what are you like, what am I like".

How it differs from synastry

Synastry compares two separate people, so it is strong at showing interpersonal dynamics — who treats whom in what way. A composite treats the relationship as a single whole, so it is considered better suited to broader questions: where is this relationship going, what is it for. Most astrologers use both — first synastry for the dynamic, then the composite for the whole.

Which relationships it is used for

Not only romantic ones. Composite charts can be cast for business partnerships, friendships, even parent-child relationships. Technically all that is required is the birth data of both people.

Synastry Chart

The comparison of two charts, the step before a composite.

Natal Chart

The single-person charts a composite takes as its input.

ALVEM's Composite Chart screen takes two people's birth details and computes the midpoints automatically.