Free Composite Chart Calculator

A composite chart is a single chart that represents a relationship as its own entity. It's calculated by finding the midpoint between each pair of corresponding planets in two natal charts: your Sun and their Sun, your Moon and their Moon, and so on through every planet and point. The result is a third chart that describes not either individual, but the relationship itself: its personality, emotional tone, purpose, and growth areas.

The composite midpoint method was popularized by astrologer Robert Hand in his 1975 book Planets in Composite. Unlike synastry, which preserves both individual charts and shows how they interact, the composite chart merges them into something new. Our calculator uses NASA's ANISE toolkit for arc-second planetary precision, then computes the exact midpoint for every pair, including the Ascendant and house cusps when exact birth times are provided.

Start with the composite Sun — its sign and house reveal the relationship's core identity and primary area of focus. A composite Sun in the 7th house, for example, centers the relationship around partnership and mutual commitment, while a 10th house Sun suggests the relationship has a public-facing quality or shared ambition. The composite Moon shows the emotional undercurrent: how both people feel when they're together and what the relationship needs to feel safe.

Angular planets — those near the composite Ascendant, MC, Descendant, or IC — dominate the relationship's expression. Venus or Jupiter angular often indicates a relationship others perceive as warm, generous, or fortunate. Saturn angular can feel heavy but builds lasting structure. The internal aspects between composite planets reveal whether the relationship's energies flow easily (trines, sextiles) or generate tension that drives growth (squares, oppositions). A composite chart with many squares isn't “bad” — it simply means the relationship pushes both people to evolve.

The composite Sun tells you what the relationship is fundamentally about — its core purpose and the identity it projects into the world. The composite Moon reveals the emotional tone: what the relationship needs to feel secure and how both people feel when they're together. Composite Venus shows how love and affection are expressed between you — the style of tenderness, generosity, and aesthetic pleasure the relationship generates. Composite Mars governs how desire and conflict operate: whether friction is approached directly, passively, or productively. Composite Saturn is the glue — its sign and house reveal where the relationship demands patience and structure, but also where it builds the most enduring foundation.

House placements matter as much as signs. A composite Venus in the 2nd house orients love around shared resources and security; in the 5th it's playful and expressive; in the 8th it's intense and transformative. Any planet in an angular house (1st, 4th, 7th, or 10th) will color the relationship's visible personality more than one tucked in a cadent house. For full sign-by-sign and house-by-house interpretations of every composite placement, visit our composite chart interpretation guide.