Synastry vs composite charts: what is the difference?

Synastry compares two individual birth charts. A midpoint composite combines corresponding planetary positions into a third, derived chart. Astrologers use them for different symbolic questions; neither method measures the quality or future of a relationship.

By AstroLuv Editorial · Published September 22, 2026 · Western astrology & reflection

Synastry keeps both people’s charts

A synastry reading examines contacts between one person’s planets and the other’s. With reliable birth times, it may also discuss angles and house overlays. Its organizing question is how two sets of chart factors relate. A useful report should identify the contact it is interpreting instead of presenting a paragraph with no connection to the chart.

A midpoint composite derives a new chart

In the common midpoint method, corresponding positions are combined: one person’s Sun with the other’s Sun, Moon with Moon, and so on. The result is a symbolic chart rather than the sky at an actual shared birth event. Astrologers often read it as a picture of relationship themes. It is not a third person’s natal chart.

A simple distinction

Imagine two people with different approaches to a project. Synastry is analogous to comparing their individual approaches; a composite is analogous to describing the shared pattern that emerges. This is an explanatory analogy, not evidence that either technique predicts how the project will go.

What birth information matters?

Both methods start with birth-chart data. Unknown times can make Moon positions uncertain and make angles or houses unreliable. A responsible report should state what was omitted or treated as approximate. Paying for more pages does not recover missing information.

Composite is not the same as Davison

You may also see a Davison relationship chart. It uses a midpoint in time and location, whereas a midpoint composite combines chart positions. Providers may offer either or both. Check which method is included so you do not buy one expecting the other.

Which should a beginner choose?

Start with a clearly explained synastry sample if you want to understand specific contacts between two charts. A composite can be a later layer if you already understand the basic vocabulary. More techniques do not automatically make a report more useful; readable explanations and transparent handling of uncertain data matter more.

Questions to ask before buying

Does the report include synastry, a composite, or both? Are house overlays interpreted or only listed? What happens if one birth time is unknown? Is the result an automated document or a consultation with a named person? The answer should be visible before payment.

When two interpretations disagree

Different methods, settings and writing styles can emphasize different themes. Do not average them into a compatibility score or keep buying reports until one gives a desired answer. Treat them as optional prompts and compare them with how the relationship actually feels and functions.

Reference

For the calculation distinction, see Astrodienst’s composite-chart reference. This describes an astrological method; it does not validate its predictions.

Astrological descriptions are symbolic traditions, not scientifically validated predictions of relationship success. Read our methodology.