Davison charts vs composite charts
Two methods for one relationship chart. One is a real moment in time; the other is not.
3 min read · Published 31 August 2026
The short answer
A composite chart averages the two people's planetary positions — the midpoint between each pair. A Davison chart instead finds the midpoint in time and space between the two births and casts a real chart for that moment and place. The key difference is that a Davison chart is an actual sky at an actual moment, while a composite is a mathematical construct that never existed.
The two methods
| Composite | Davison | |
|---|---|---|
| Method | Midpoint of each pair of planetary positions | A chart cast for the midpoint date, time and place |
| Is it a real sky? | No — the positions never occurred together | Yes — a real moment that actually happened |
| Internally consistent? | Not necessarily | Yes, by construction |
| Needs birth times? | For angles and houses | Yes, and birthplaces |
| More common | Yes, by a wide margin | Less used |
The consistency row is the substantive difference and it is rarely explained. In a composite chart, Mercury can end up more than 28 degrees from the Sun — which is astronomically impossible, since Mercury never strays that far. The composite is a set of averages that does not describe any possible sky.
Why that matters
A Davison chart can be read with the ordinary rules, because it is an ordinary chart. Retrogrades are real, planetary distances are possible, and the whole apparatus of dignity and sect applies as normal.
A composite chart cannot always be read that way. If Mercury sits 40 degrees from the Sun, any technique assuming real planetary behaviour breaks down.
Composite advocates would respond that it is a symbolic construct, not a sky, and should not be judged by astronomical standards. That is a coherent defence. It also means the composite is a different kind of object from every other chart in astrology, which is worth knowing before treating its output the same way.
How Davison works
Take the two birth moments and find the temporal midpoint — if one person was born in 1990 and the other in 1996, the midpoint is 1993.
Take the two birthplaces and find the geographic midpoint in latitude and longitude.
Cast a normal chart for that time at that place. That moment genuinely occurred, and the sky it describes is one that actually existed.
One consequence people find striking: the Davison chart has a real date, so it can itself be progressed and transited using ordinary techniques. A composite chart cannot be progressed in the same way, because it has no date.
The shared limit
Neither has been shown to describe a relationship, and neither can tell you whether one will last.
Both also share a structural oddity worth noticing: a relationship chart exists from the moment two people were born, long before they met. Whether that is a feature or an incoherence depends on assumptions about time that neither method states.
AsterNym computes neither. Its match compares two charts directly through synastry, BaZi and numerology, shows the scoring, and presents the result as a conversation starter rather than a verdict — which is the most a comparison can honestly offer.
Common questions
- What is the difference between a composite and a Davison chart?
- A composite averages each pair of planetary positions between two charts. A Davison chart finds the midpoint in time and space between the two births and casts a real chart for that moment and place, so it describes a sky that actually existed.
- Why can a composite chart be astronomically impossible?
- Because averaging positions independently can place Mercury more than 28 degrees from the Sun, which never happens in reality. The composite is a mathematical construct rather than a description of any possible sky.
- Can a Davison chart be progressed?
- Yes, because it has a real date. Ordinary progression and transit techniques apply to it exactly as they would to a natal chart. A composite chart has no date, so it cannot be progressed in the same way.
- Which relationship chart is better?
- Neither has demonstrated validity. Davison has the advantage of being internally consistent and readable with ordinary techniques; composite is far more widely used. Both exist from the moment two people were born, long before they met.