This drawing places two calculated natal charts beside their derived midpoint composite in one wheel. The outer ring belongs to Person A, the middle ring to Person B, and the inner ring to the composite. The positions and drawing here are independently calculated and laid out; degrees can differ from a Swiss Ephemeris output.
What is averaged
For each matching planet, the calculator measures the shorter arc around the tropical zodiac and places the composite point halfway along it. The two natal Ascendants, Midheavens, and matching house cusps are treated the same way. This is the midpoint house method. It is different from the reference-place approach, which starts with the composite Midheaven and rebuilds the house frame from a chosen latitude. The chart here asks for both birth locations because the original natal angles and house cusps need each person's geographic horizon.
Consider natal Venus at 350° and 10°: the short arc crosses 0° Aries, so its midpoint is 0°, not 180°. A pair exactly 180° apart has two equally short arcs and two candidate midpoints. Rather than silently choosing one, this tool prints both. Near opposition, a small birth-data correction can move the chosen short arc to the other side of the wheel. The result is especially sensitive for a natal Moon when a birth time is uncertain.
How to use the three rings
First inspect the two natal positions before reading their midpoint. A close composite Sun–Moon contact, for example, is made from two separate pairs of source positions. The composite is a symbolic pattern, not a sky observed at a third time. Read the colored rings by their legend and use the table for exact degrees; symbols can visually overlap when several planets occupy a small arc. The tables show every planet in both natal charts and the composite. A separate expandable table records the Ascendant-related house-cusp calculation for all twelve houses.
The thin center rays show cusp midpoint longitudes. Zodiac cusp averaging is a mathematical convention; the resulting sequence is not guaranteed to be a physically realizable house geometry. For this reason the page does not assign composite planets to numbered houses or claim that the center ring is a possible birth chart. It also leaves Mercury and Venus at their calculated positions rather than applying an optional 180° reversal sometimes used by chart-drawing conventions.
Birth records and interpretive limits
Enter each person's recorded local clock time, birthplace latitude and longitude, and the UTC offset that actually applied on that date, including historical daylight saving time. The form does not infer legal time zones from place names. A wrong offset changes natal angles and houses and therefore their midpoint results. Placidus, Campanus, or Regiomontanus may fail at extreme latitudes; the underlying house engine reports a Porphyry fallback. If the two natal charts end up using different effective systems, examine the labeled result before comparing cusps.
The wheel is a way to inspect arithmetic and astrological symbolism. It is not a relationship score and cannot determine consent, safety, or future conduct. Compare the people and their real circumstances when making decisions.