Relationship Charts in Astrology: Composite and Synastry

Astrologers use two types of charts to read relationship potential: composite (combined) and synastry (side-by-side). Here’s a guide to both relationship charts.

Raise your hand if you’ve ever used astrology to decipher a relationship’s potential. Heck, you may have an app on your phone to check cosmic compatibility on the fly. (We have a few of ‘em.) No matter the nature of a relationship, astrology is the best secret decoder ring for navigating interpersonal dynamics. 

Understanding someone else’s natal chart is a great place to start. The map of the stars at their time of birth is their cosmic blueprint, revealing what makes them tick. And if what makes them tick is something you want to “tok” right along with, we recommend casting both these two types of relationship charts: composite and synastry.

What is the difference between a composite chart and a synastry chart?

A composite chart

Combines two charts into one

A synastry chart

Is a side-by-side comparison of both charts, focusing on the angles (aspects) between planets and houses

Composite chart: Combine

In this type of relationship chart, 2 become 1

Did you know that every relationship has an astrological chart of its own? What would it look like if you and another person merged in perfect harmony—or met each other halfway in an ideal compromise? This chart provides a cosmic care and feeding manual for any two people.

Just like your individual charts, your relationship has a zodiac GPS for each of the planets. What unique needs must be tended to in order to keep your union thriving? The composite/midpoint chart can reveal this!

This unique relationship map is created by taking two charts and finding the midpoint between each corresponding planet. A third chart is created—one that’s a blend between the two charts being studied.

Many people believe that relationships are like a third person (“there’s you, me and the relationship,” as the saying goes). The composite chart shows the spiritual potential—and the challenges—of joining forces with another person.

Read more about Composite charts

Comparison chart/method (Synastry): Side-by-Side

In this type of relationship chart, a snapshot of your charts is created

In comparison charts, we compare the planets in your chart and the other person’s chart. We lay the charts side-by-side and analyze where, for example, the moon in your chart is versus the moon in someone else’s chart. This is advanced astrology, and if you’re new to the star game, we recommend booking a reading with a professional for this type of relationship chart.

The relationship between two planets in question can determine your interpersonal dynamics. Will you get along smoothly or need to compromise? We look at two main things in synastry charts to determine this.

1. The angles (aspects) between planets

If planets are square 90º or opposite each other, there may be tension and constant balancing. If planets are trine (120º) they will work in harmony. This just scratches the surface of a synastry chart—you could spend years unpacking the interplanetary relationships between two charts. 

2. What houses planets fall into in each other’s chart

This type of synastry reading involves a double-wheel chart, comparing (and interchanging) into what houses each person’s planets fall. A reading like this can reveal what areas of life will be more activated by the other person’s planets.

Read more about Synastry charts

Decode your relationship charts

Understanding how the planets and zodiac signs influence us is part of this “decoding.” There is no straightforward or right answer to the question, “Are we compatible?” We’ve seen relationships with lots of squares and oppositions that have been dynamic and sexy for decades. 

If you’re investing time and energy into building a bond, we recommend using relationship charts as a tool to gain awareness of your interpersonal dynamics. 

After all, once you evolve past the honeymoon phase, your partner can become your greatest teacher for self-discovery. Sometimes a “study in contrasts” will bring out parts of your personality you didn’t know existed. This can be triggering, confronting, exciting––all of it! Astrology is one of the best tools for helping you stay in the game!


The AstroTwins

Identical twin sisters Ophira and Tali Edut, known as The AstroTwins, are the founders of and the authors of multiple bestselling astrology books. Their horoscopes reach millions here and through their resident astrologer column at ELLE Magazine.