What Is a Davison Chart?: The Relationship's Own Birth Chart

The calculator averages the two birth instants on the Julian Day scale. For births at 00:00 UT on January 1, 1960 and January 1, 1970, the interval is 3,653 days. Its midpoint is December 31, 1964 at 12:00 UT. For noon and 6 PM on the same date and in the same time zone, the midpoint is 3 PM.

For location, Augurine averages the latitudes and uses the shorter arc between the longitudes. It then casts a chart for that moment and place. Davison's own procedure selects one of the two natal MC midpoints and adjusts local mean time until the chart has that MC. His arithmetic longitude convention can also differ from this calculator's shorter-arc choice when the signed longitudes are more than 180° apart.

In this uncorrected midpoint variant, a four-minute error in one birth time shifts the relationship time by two minutes. Equal four-minute errors in both inputs shift it by four minutes. The resulting change in the Ascendant depends on latitude and the part of the zodiac rising, so there is no universal degrees-per-minute conversion.

Read it the way you would read any natal chart, because that is what it is. The Sun shows the relationship's purpose and identity. The Moon describes the emotional baseline between the two people. The Ascendant tells you how the couple comes across to the outside world. Aspects between planets describe the relationship's internal dynamics, not the dynamics between two individuals.

A Venus-Saturn conjunction in the Davison, for example, describes a relationship that fuses affection with responsibility. A Mars-Jupiter trine describes a relationship that energizes and expands both people. The distinction from synastry is that these are aspects within the relationship entity, not between two separate charts.

House emphasis matters. A Davison chart with most planets above the horizon suggests a relationship that plays out publicly. Most planets below the horizon points to something more private. Angular planets (conjunct the ASC, MC, DC, or IC) are the loudest voices in the relationship and tend to describe what others notice about the couple first.

A Davison chart corresponds to a real moment, so practitioners can apply transits, secondary progressions, solar arc directions, and solar returns to it. Composite timing also has published methods. In Planets in Composite, Robert Hand describes progressing each person's chart first and then taking the composite of those progressed charts.

In practice, this means you can track candidate testing periods, growth windows, and times when the bond may deepen or come under pressure. The Davison responds to the same planetary cycles used in individual timing work, which gives couples and astrologers a timeline to compare with lived events rather than only a static snapshot.

The Davison provides a single chart epoch for timing work. A progressed composite instead requires a declared method for combining the two people's progressions. Compare either approach with lived events and keep the method consistent across the reading.

Townley, who codified the composite chart, was skeptical of the Davison. His argument: the outer planets will land near their composite positions regardless (because they move slowly), but the angles will be "all over the place." Hand largely agreed with this criticism. The counterargument is that Davison practitioners find the angles interpretively useful in practice, whatever the theoretical objection.

The Davison chart also works only for two people. You cannot extend it to groups the way you can with composites, which can midpoint three or more charts. And because the midpoint date may fall decades before either person was born (when there is a large age gap), some of the resulting planetary positions can feel disconnected from either person's lived experience. The technique works best when the two birth dates are relatively close in time.