Relationship Astrology: The Differences Between Synastry and Composite Astrology Charts

Written by Dayva Segal
Updated: November 20, 2023
Share on:


Is our romantic compatibility written in the stars? Many have wondered. Astrologers have two ways to look at compatibility using natal astrology charts: synastry and composite astrology charts.

While most people use both synastry and composite charts for romantic relationships, they can be used for any partnership. These charts can also provide insight into friendships, business partnerships, and other connections.

Like everything in astrology, it’s important to take things with a grain of salt. There are infinite ways to interpret charts and numerous perspectives on how astrology can affect us. So, it’s always appropriate to throw out things that don’t resonate with you from an astrology reading and keep only what feels true or helpful to you.

Each synastry or composite astrology chart will have some difficult qualities and some easier ones. Your relationship isn’t doomed just because there is something challenging in the chart. No relationship is a complete walk in the park. Relationships take work, and often, a bit of compromise. Each challenge in all areas of astrology, but especially in relationship astrology, is an opportunity to learn and grow.

What is a Synastry Chart in Astrology?

Astrology birth chart compatibility for partner with heart. Astrological Compatibility men and women, synastry layout. New age astrological

This is an example of a synastry chart, which shows two peoples’ natal placements.

©Worarat Ngamkamollert/iStock via Getty Images

A synastry chart is a side-by-side comparison of two people’s natal astrology charts. Astrologers use these to see aspects between the different planets, angles, and other bodies in the two charts. A synastry chart looks like two circles, with one inside the other. The outer circle contains all of one partner’s placements, and the inner circle contains the others. Sometimes, there will be a third inner circle that has lines showing the aspects on the chart to make them easier to see.

Synastry charts help people see places of flowing and blocked energy in a relationship. They show where things are easy, and where they are hard. They can help to explain someone’s behavior and offer ideas for solutions to relationship issues. It helps people to see similarities and differences between themselves and their partner.

What is a Composite Chart in Astrology?

Young couple making pancakes at home. Loving couple having fun while cooking.

Both synastry and composite charts can give couples information about their relationship.

©Just Life/

Composite charts are another way of determining compatibility in astrology. These charts take two peoples’ natal charts and combine them into one chart that represents the relationship. Astrologers find the midpoint between each planet in the two charts to determine the placements. This method creates an entirely new chart that represents the connection between two people rather than a comparison between their separate charts.

Similarities and Differences Between Synastry and Composite Astrology Charts

Both synastry and composite charts are used in relationship astrology. They both compare two peoples’ natal astrology charts, just in different ways. You may see similar issues in both a synastry and composite chart for the same couple. However, sometimes they show different matters to focus on.

A synastry chart is an exploration of two peoples’ separate dynamics and how that might result in ease or conflict. A composite chart is a totally new chart that represents the relationship. Some believe that the outcome of the relationship, such as marriage or a breakup, can also be found in a composite chart. However, other people believe that composite charts are not so determinative. They believe that it is more of a psychological tool that people can use to determine points of pain and points of ease in the relationship.

One way to look at is that a synastry chart is a comparison of two people and how they might show up to a relationship and interact with each other. A composite chart represents how that same relationship might interact with or appear to the world.

Relationship Charts for More Than Two People

One of the main differences between a synastry and a composite chart is the number of people. Synastry charts can really only be done for two people at a time. To compare charts for a group of three, you’d need to create multiple synastry charts; one for each possible pairing in the group. However, it is possible to do a composite chart for three people. This is useful for love triangles, people in open-relationship triads, groups of friends, and coworkers.

One of the only places to find a three-person composite astrology chart, outside of seeing a professional astrologer, is This is the site of AstroDienst, a Swiss astrology company that has been a leader in computer-generated astrology charts since the 1980s. Their site has been online since 1996 and is one of the most thorough and popular astrology websites today.

Some people also use a couple’s composite chart plus another person’s chart to create a new synastry chart that may show how someone might interact with a couple or an existing relationship.

The photo featured at the top of this post is © Andrey_Popov/

Share on:
About the Author

Dayva is a writer at A-Z Animals primarily covering astrology, animals, and geography. She has over 12 years of experience as a writer, and graduated from Hofstra University in 2007 with a Bachelor of Science in Music and a Minor in French. She has also completed course work in Core Strengths Coaching, Hypnotherapy, and Technical Communication. Dayva lives in the SF Bay Area with her cute but very shy cat, Tula.

Thank you for reading! Have some feedback for us? Contact the AZ Animals editorial team.