Free Composite Chart Calculator

What a composite chart represents

A composite chart is not a blend of your two personalities and not a prediction about your future together. It is a third chart, built from the midpoints of your two charts, that astrologers read as a symbolic stand-in for the relationship itself. Its own Sun, its own Moon, its own house emphasis.

That makes it a different kind of answer than synastry. Synastry tells you how you affect each other; a composite chart tells you what the relationship looks like from the outside, as though it were a person in its own right.

How the midpoint is calculated

For every planet, this calculator finds the shortest arc between your placement and theirs and takes the point exactly halfway along it, the standard near-arc convention. The same math derives the composite Ascendant and Midheaven from your two Ascendants and Midheavens.

There is no real date, time, or place for a composite chart. It is pure arithmetic on two real charts, not a chart for an actual moment. That is the key difference from the Davison method below.

Reading the composite Sun, Moon, and Ascendant

The composite Sun describes the shared purpose or identity the relationship organizes around, what it is fundamentally about. The composite Moon describes its emotional undercurrent: what the relationship needs to feel secure. The composite Ascendant describes how the relationship presents to the outside world, how other people experience you as a pair.

Read these three before working through the aspects, the same order that works for reading any single chart.

Why composite houses are equal houses

Because there is no real location or time for a composite chart, this calculator does not run a normal house calculation. Instead it lays out twelve equal 30-degree houses starting from the composite Ascendant, the standard convention when no synthetic location is used, and the same reason the house-system dropdown on this page has no effect on a composite result. A Davison chart, by contrast, gets real houses, because it is cast for a real moment and place.

What a composite chart can't tell you

Composite planets never carry retrograde status. Retrograde motion describes a planet's apparent movement from a real observation point, and a midpoint placement has no such point to measure from, showing a retrograde symbol here would imply a precision the technique doesn't have.

A composite chart also doesn't replace synastry. It says nothing about how you specifically affect each other day to day; it only describes the relationship as a standalone entity. Most astrologers read the two together.

Composite vs Davison vs synastry

All three techniques start from the same two birth charts and answer different questions. Synastry keeps both charts separate and compares them directly. A composite chart merges them into midpoints, an abstraction with no real moment behind it. A Davison chart also merges the two people into one chart, but finds a literal midpoint moment in time and space and casts a genuine chart for it, real houses included.

If you want the more commonly used of the two derived-chart methods, that's composite; if you'd rather work from an actual astronomical event, use the Davison chart calculator instead.