Synastry
Synastry compares two birth charts to show your zodiac and love compatibility across emotion, communication and shared direction. Provide accurate birth data to calculate aspects and house overlays, then read the report as a structured assessment of harmony, tension, and growth areas. Use the sections to understand how the connection operates and where it needs attention.
What synastry is
Synastry lays two natal charts over each other and looks at how one person's planets interact with the other person's. Unlike comparing Sun signs alone, it takes the Moon, Venus, Mars, the ascendant and the aspects between them into account, so the picture is far more precise. Two Aries can get along brilliantly or not at all, depending on the rest of their charts.
What information you need
You enter the same details for both people:
- Name, so the reading is personal and it is clear who is who.
- Date of birth: it sets the positions of the Sun, the Moon and the planets.
- Time of birth, as exact as possible. The ascendant changes roughly every two hours, and the houses even faster.
- Place of birth, for the time zone and the house positions.
- If you don't know the exact time, enter an approximate one. The planets will still be accurate, but the ascendant and houses may be off.
What a synastry chart looks at
Sun and Moon
The basis of compatibility: how your identities and emotions fit together and whether you feel accepted by each other.
Venus and Mars
Attraction, romance and passion: what draws you to each other and how each of you expresses love.
Mercury
Communication: how you talk, how you argue and how easily you clear up misunderstandings.
Jupiter
Where you bring each other growth, optimism and luck.
Saturn
Commitment and endurance: what holds the relationship together in the long run, and where pressure and limits appear.
Ascendant and houses
How the other person perceives you at first sight and which areas of life your relationship activates most.
How to read the report
- Harmonious aspects (trines and sextiles) show where things come easily and naturally between you.
- Tense aspects (squares and oppositions) bring friction, but also attraction and growth. Many strong relationships have plenty of them.
- A conjunction joins two planets and amplifies their theme, for better or as a challenge.
- The most important aspects are those between the Sun, the Moon, Venus, Mars and the ascendant.
- Look at the whole picture, not a single aspect. No relationship is perfect, and no single aspect decides a relationship on its own.
Synastry or a natal chart?
Synastry shows the relationship between two people. If you first want to understand yourself better, create your own natal chart, and for a forecast for the year ahead, your personal annual horoscope. We also write about how you love and what attracts you in Venus in the signs.
Frequently asked questions about synastry
Is the synastry chart free?
Yes. You get the report for free and with no sign-up. There is a short 30-second pause between two AI readings.
Do I need to know the exact time of birth?
It is recommended. Without the exact time the planet positions are still correct, but the ascendant and houses may be wrong, and with them part of the reading.
Is synastry only for romantic relationships?
No. The same comparison also shows the dynamics of a friendship, a business partnership or a parent and child relationship, although the reading focuses mostly on couples.
What if there are a lot of tense aspects?
It does not mean the relationship cannot work. It shows where you need more understanding and effort, and often where the attraction is strongest.
What is the difference between synastry and sign compatibility?
Sign compatibility compares only Sun signs, so it gives a general answer. Synastry compares the full natal charts, which is why two people with the same signs can get very different results.
How does the AI create the reading?
The positions of both people's planets and the aspects between them are calculated from the date, time and place of birth. The AI then interprets the most important connections and writes a report on harmony, tensions and areas of growth.