Composite Chart Calculator — Relationship Midpoint Chart
A composite chart takes two real natal charts and builds one new chart from the genuine zodiacal midpoint of every planet pair, plus a Porphyry house system built around the composite Ascendant and Midheaven. It's read as the chart of the relationship itself, distinct from synastry's side-by-side comparison of the two original charts.
Because it's a real chart in its own right, it comes with a real Ascendant, Midheaven, and full set of house cusps — so a composite Sun or Moon can be read in its own composite house, the same way any natal placement would be, rather than only compared point-by-point against the two original charts.
Frequently Asked Questions
What's the difference between a composite chart and synastry?
Synastry compares two real charts side by side and reads the angles between them; a composite chart merges the two into one new chart instead, where every planet sits at the real zodiacal midpoint between that planet's position in each birth chart.
Is the composite Sun the midpoint of both people's actual Suns?
Yes — this tool finds each planet's true zodiacal midpoint (the shorter arc between the two positions, not a naive numeric average), so the composite Sun is the genuine midpoint of Person A's Sun and Person B's Sun.
Does the composite chart use its own house system?
Yes — this tool builds a full Porphyry house system around the midpoint positions, using the composite of each person's Ascendant and Midheaven as the chart's own angles.
Can a composite chart work if the two people never met in person?
Yes — every position is a real mathematical midpoint between two independently computed birth charts, so the composite is calculable for any two known birth data sets.
Is a composite chart a real technique or a modern invention?
It's a 20th-century technique from astrologers working in the 'combined charts' tradition — newer than natal astrology or synastry, but still a traditional method within modern relationship astrology.