Composite chart calculator
Create a planetary midpoint chart from two births. Each planet sits halfway along the shorter zodiac arc between its natal positions.
Method and limits
We calculate the natal longitudes with Astronomy Engine and derive short-arc midpoints. A composite is symbolic and may contain combinations impossible in a real sky, such as Mercury opposite the Sun. It is not an astronomical event or a scientific relationship score. See Astrodienst’s chart-type explanation.
Frequently asked questions
How is this composite chart calculated?
For each planet, take the midpoint on the shorter arc between its two natal longitudes. For example, 350° and 10° give 0°, not 180°. Exactly opposite positions have two equally valid midpoints, so this tool marks them ambiguous and excludes their aspects.
Is a composite the same as synastry or a Davison chart?
No. Synastry compares two separate charts. A composite constructs planetary midpoints. A Davison chart uses a midpoint in birth times and places and is a different method.
Why are there no composite houses?
House and angle construction methods differ. This tool provides the planetary midpoint chart and its aspects; it does not assign composite houses or a composite Ascendant.
Compare the two natal charts with synastry
Astrology is a symbolic and cultural tradition. The planetary positions on this site are calculated with astronomical accuracy; the interpretations describe what astrologers associate with them and are not scientifically validated predictions about personality, relationships or the future.