Guide
Synastry Chart vs Composite Chart
Both tools describe relationships — they answer different questions. Use synastry for how two people interact; use composite for the relationship as one chart.
Synastry compares two birth charts directly: planetary aspects between people and house overlays that show where each person lands in the other’s life. It is best for chemistry, attraction, communication patterns, and day-to-day interaction.
Composite averages planetary positions into one midpoint chart for the relationship as an entity. It is useful for shared purpose, the public face of the bond, and the relationship’s own lifecycle — not mainly a person-to-person scorecard.
Many astrologers use both. If you only have time for one free calculation, pick by question: “How do we affect each other?” → synastry calculator. “What is this relationship like as a whole?” → composite chart calculator.
Side-by-side comparison
| Synastry | Composite | |
|---|---|---|
| Method | Compare two birth charts | Planetary midpoints |
| Main question | How do we affect each other? | What is this relationship like? |
| Best for | Attraction, compatibility, interactions | Relationship identity and dynamics |
| Main techniques | Aspects + house overlays | Composite planets, houses, and aspects |
| Free tool on this site | Synastry calculator · synastry report | Composite chart calculator |
Choose synastry when…
- You want chemistry, friction, and conversation patterns.
- You care who activates whose houses.
- You want a written compatibility report in plain language.
Choose composite when…
- You want one chart for the relationship itself.
- You care about shared purpose, public image, and the bond’s “weather.”
- You already know the interaction story and want the midpoint field next.
How to read either chart
Technique still matters after you pick a tool. For person-to-person contacts, follow a steady order — lights, personal planets, tight aspects, then overlays — in how to read a synastry chart. Composite results on this site walk midpoints in a similar practical order after you calculate.
Frequently asked questions
- What is the difference between synastry and a composite chart?
- Synastry compares two birth charts through aspects and house overlays. A composite chart averages planetary positions into one midpoint chart that describes the relationship as its own entity.
- Should I calculate synastry or composite first?
- Start with synastry if you want chemistry, attraction, and how you affect each other. Use composite when you want the relationship’s shared identity, purpose, and day-to-day field.
- Can I use both synastry and composite together?
- Yes. Many astrologers read both: synastry for interaction patterns and composite for the bond as one chart. The same birth data powers both tools on this site.
Calculate both views with the same birth data
Run a free synastry chart for interaction, or a free composite chart for the relationship as one midpoint wheel — no account required.
Related guides & tools
- Synastry Chart CalculatorCompare two birth charts for aspects, house overlays, and scores.
- Free Synastry ReportA plain-language reading of your strongest relationship patterns.
- Synastry AspectsHow planet-to-planet contacts shape chemistry and friction.
- Synastry HousesWhere each person’s planets land in the other’s chart.
- How to Read a Synastry ChartA practical order for aspects, planets, and overlays.
- Composite Chart CalculatorSee the relationship as one midpoint chart.