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Synastry

Synastry calculator: Compatibility is not one number.

Explore two charts across Love, Chemistry, Emotional Bond, Communication, Commitment and Intensity. Reflect on each theme separately, without an overall compatibility percentage or confusing intensity with quality.

Three connections are free. The full report is in Astro-Plus; see the current price and subscription terms.

Free preview

Explore three chart connections between you.

Enter both birth dates and cities. Add each time if known, or select “Birth time unknown.” The mobile app’s shared engine calculates up to three connections here—not a full relationship report or a compatibility verdict.

Want to continue in your account? Open the Synastry Room.

See how the preview works with two fictional birth records. No account or payment required. Your entries stay unchanged.

View the fictional birth records
  • A · 1990-03-15 · 10:30 · Madrid · Europe/Madrid
  • B · 1992-11-07 · 18:20 · Berlin · Europe/Berlin
Person A
Person B

Choose each city from the suggestions. This preview is calculated in your browser; birth details and the result are not sent to a server or saved. If you consented to analytics, only preview completion is measured.

How to read relationship compatibility: a worked example

These two placements are a hypothetical teaching example, not a real customer chart or a forecast for today. Assume both birth times are reliable.

  1. Calculate the contact first

    Suppose person A’s Moon is at 10° Taurus and person B’s Venus is at 12° Taurus. Their zodiac longitudes are 40° and 42°. The 2° separation is 2° away from an exact conjunction: a Moon–Venus conjunction with a 2° orb. Sharing a Sun sign does not change this calculation.

  2. Consider each person’s needs separately

    The Moon can be read symbolically as emotional needs and Venus as ways of showing affection. Ask, “One person enjoys offering attention, but does the other experience it as support?” That is more useful than declaring them compatible. Both people’s answers matter; a chart cannot supply those answers for them.

  3. Do not turn one contact into a verdict

    This contact contributes to the love and emotional-bond themes. It is not a chemistry, communication or long-term commitment score on its own. Examine other contacts and, when the birth times are known, house overlays in both directions. Several independent indicators can support a recurring theme. Rewriting the same contact in reverse does not create new evidence.

If a birth time is unknown, do not apply this example’s precise Moon degree to your own result. Moon positions are approximate; that person’s Ascendant, houses and overlays into those houses are omitted. Guessing a city or time does not make missing information reliable.

Finish with a real conversation: “What kind of support would you like from me after a difficult day?” Strong attraction does not guarantee trust or relationship quality. No chart can assess mutual respect and boundaries in place of the people involved.

Calculation source: Astronomy Engine. Astronomy Engine is used to calculate planetary positions. Accurate astronomical calculations do not scientifically validate astrological relationship interpretations.

Six themes, read separately.

The full reading considers planetary contacts, house overlays in both directions and recurring themes. Unknown time or location means houses and angles are omitted; scores are not verdicts.

Love

How do you show that you value each other?

Sun, Moon and Venus contacts can prompt reflection on appreciation and closeness. Affection also grows through mutual actions, not a score.

Read from

  • Sun ☉ Venus
  • Moon ☽ Venus
  • Venus ♀ Jupiter
  • 5th and 7th houses

Communication

Can you actually hear each other in an argument?

Mercury contacts may point to easier or more demanding communication patterns. No single aspect determines how a conversation ends.

Read from

  • Mercury ☿ Mercury
  • Mercury ☿ Moon
  • Mercury ☿ Venus
  • Mercury ☿ Saturn

Chemistry

Is there a real pull between you?

Venus–Mars contacts may suggest how attraction and initiative meet. Even a close contact cannot predict longevity, so chemistry has its own axis.

Read from

  • Venus ♀ Mars
  • Mars ♂ Pluto
  • 5th and 8th houses
  • Mars ♂ Uranus

Emotional bond

Do you feel safe there?

Moon and Sun–Moon contacts offer a way to reflect on emotional needs. Feeling safe also depends on what people actually do together, beyond any chart aspect.

Read from

  • Sun ☉ Moon
  • Moon ☽ Moon
  • Moon ☽ Venus
  • 4th house

Commitment

Will this carry weight over time?

Saturn contacts may raise questions about boundaries, responsibility and long-term expectations. More Saturn does not automatically make a relationship durable or difficult.

Read from

  • Saturn ♄ Sun
  • Saturn ♄ Moon
  • Saturn ♄ Venus
  • 7th house

Intensity

Why might this connection feel so strong?

Pluto, lunar nodes and 8th/12th-house contacts can raise questions about depth and boundaries. Intensity is not relationship quality: a strong pull does not imply emotional compatibility.

Read from

  • Pluto contacts
  • Lunar nodes
  • 8th and 12th houses
  • Chiron

Synastry or composite?

They are not rivals; they answer different questions. Baby Astro computes both — knowing which one you need just makes it faster.

What it answers
SynastryWhat do you two do to each other?
CompositeWhat is this relationship, on its own?
How it is built
SynastryTwo charts overlaid; the aspects between them are read.
CompositeOne new chart, built from the midpoints of both.
Best at describing
SynastryAttraction, friction, what you each trigger in the other.
CompositeThe relationship's purpose, tempo and public face.
When to read it
SynastryEarly on, or when untangling a conflict that keeps repeating.
CompositeOnce it institutionalises — living together, partnership, marriage.
Its blind spot
SynastrySays nothing about where the relationship itself is going.
CompositeSays nothing about the personal chemistry between you.

Frequently asked questions

Two charts, six themes.

Enter both birth dates and cities. Add known times; mark unknown ones in the form. A limited preview explains the uncertainty alongside the results.

Compare two charts for free