Synastry Chart: What It Is, How It Works, and How to Read Yours
A synastry chart is what astrology uses to look at two people at once. Instead of reading one birth chart in isolation, you lay two charts over each other and see where they meet — where the sparks fly, where things feel easy, and where you'll have to do a little work. It's the closest thing astrology has to a relationship map, and you can build yours below in a couple of minutes.
Person 1
Person 2
Enter birth date and place for both people to continue. Birth time is optional.
By continuing you confirm you are at least 16 years old (or have your parent or guardian's permission) and agree to our Terms and Privacy Policy. Astrological readings are AI-generated for entertainment and self-reflection — they are not professional advice. See our Disclaimer.
What Is a Synastry Chart?
A synastry chart is a side-by-side comparison of two people's birth charts. You take each person's natal chart — the snapshot of the sky at the exact moment and place they were born — and overlay them to see how one person's planets land on the other's.
That overlay is the whole point. Your Venus might sit right on their Moon. Their Mars might square your Saturn. Each of these meeting points says something about how the two of you actually feel to each other day to day, not just in theory.
Synastry is most often used for romantic compatibility, but it works for any relationship — friends, family, business partners, anyone whose chart you want to read against your own. If you've ever wondered why one person feels instantly familiar and another feels like hard work, this is where astrology goes looking for an answer.
How a Synastry Chart Works
A synastry chart works by measuring the angles — called aspects — between one person's planets and the other's. Those aspects are what turn two separate charts into a single story about the relationship.
Here's what the chart is actually showing you:
- The aspects between charts. The angles your planets make to theirs — conjunctions, trines, squares, oppositions. Easy aspects (like trines and sextiles) tend to feel smooth and supportive, while hard aspects (like squares and oppositions) bring tension, attraction, and the friction that makes a relationship grow.
- The planets involved. Sun and Moon contacts speak to identity and emotional safety, Venus and Mars to attraction and chemistry, Saturn to commitment and staying power, and the outer planets to the deeper, fated-feeling pulls.
- The houses each planet falls in. Where your partner's planets land in your chart shows which areas of life they light up for you — home, romance, work, or the more private corners.
No single aspect makes or breaks a relationship. A synastry chart is a pattern, not a verdict — you read the whole picture rather than any one line in it.
Create Your Free Synastry Chart
The easiest way to understand synastry is to see your own. Enter both birth dates, times, and places below and the free synastry calculator will build your combined chart — mapping every planet, aspect, and house overlay between the two of you.
For the most accurate reading you'll want exact birth times for both people, since the houses and the faster-moving points shift through the day. If you don't have a birth time, you can still generate a chart — just know that the house overlays and Moon position may be approximate.
Once your chart is ready, you can come back to the sections above to start making sense of the aspects you see.
Person 1
Person 2
Enter birth date and place for both people to continue. Birth time is optional.
By continuing you confirm you are at least 16 years old (or have your parent or guardian's permission) and agree to our Terms and Privacy Policy. Astrological readings are AI-generated for entertainment and self-reflection — they are not professional advice. See our Disclaimer.
Explore Synastry Further
A synastry chart gives you the map — these guides help you read it. Once you've created yours, here's where to go next:
- Synastry meaning. A deeper look at what synastry is and how astrologers interpret a combined chart, step by step.
- Synastry compatibility. How to weigh the easy and hard aspects together and read what your charts say about the relationship as a whole.
- Synastry aspects. Detailed breakdowns of the specific contacts — like Sun conjunct Moon or Venus square Mars — and what each one tends to bring.
- Free synastry chart. Build a free two-person chart and see how your planets meet.
- Birth chart compatibility. The broader question synastry answers: how two whole charts fit together, not just two sun signs.
- Composite chart. Blend both charts into one and read the relationship as a chart of its own.
If you're new to charts in general, it helps to understand how a single birth chart is built before you compare two.