Check astrology compatibility by comparing two natal charts, not just two Sun signs. This free synastry calculator looks at Moon, Venus, Mars, Mercury, Saturn and other chart-to-chart aspects connected with emotional fit, attraction, communication and relationship patterns.
Birth times improve synastry precision, but you can start without them.
STARIS IS CALCULATING
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LOVE COMPATIBILITY & SYNASTRY
A love compatibility calculator based on birth charts uses synastry—the comparison of one natal chart with another. Instead of matching only two zodiac Sun signs, Staris compares planetary contacts connected with emotional needs, attraction, communication and longer-term relationship themes.
SYNASTRY CALCULATOR
Synastry compares the planets and chart points in two birth charts and measures the aspects between them. A Moon–Venus contact describes a different relationship theme from Mercury–Mercury, Venus–Mars or Saturn contacts.
That makes a synastry calculator more detailed than a basic zodiac compatibility checker that only compares two Sun signs.
LOVE & ATTRACTION
Astrologers often look at Venus and Mars for attraction, the Moon for emotional security, Mercury for communication and Saturn for commitment, pressure or durability. Smooth aspects can feel easy, while tense aspects can create friction and still feel highly magnetic.
Staris separates these dimensions so one overall score does not hide where the strongest connection or challenge actually comes from.
BIRTH DATE & TIME
Yes. Many planetary relationships can still be compared from birth dates, but exact birth times add the Ascendant, houses and other time-sensitive chart factors.
If one or both times are unknown, Staris keeps the result focused on the chart evidence that can be supported instead of pretending to have exact angles or houses.
RELATIONSHIP REALITY
No compatibility score can measure honesty, safety, shared values, communication effort or whether two people want the same future. Astrology can describe symbolic relationship patterns, not decide the outcome.
Use the result as a way to understand chemistry, emotional differences and recurring dynamics—not as a verdict on whether to stay together.
COMMON QUESTIONS
Common questions about astrology compatibility, synastry calculators, zodiac matches, birth dates and birth chart compatibility.
A birth-chart compatibility calculator creates or reads two natal charts and compares the aspects between them. Staris groups important synastry contacts into emotional connection, attraction, communication and longer-term themes.
A synastry calculator compares two birth charts to show how one person’s planets connect with the other person’s planets and chart points. It is a fuller astrology compatibility method than comparing Sun signs alone.
Yes, birth dates provide useful planetary information. Exact birth times and places can add rising signs, houses and angles, which make the comparison more detailed when those times are known.
No. You can still compare many planetary aspects without exact times. Birth times improve the result by adding time-sensitive chart factors such as the Ascendant and houses.
No. Astrology cannot prove that someone is a soulmate, secretly loves you, will return or will stay. It can only be used as a symbolic way to explore relationship patterns.
There is no single universal placement. The Moon can describe emotional needs, Venus and Mars attraction, Mercury communication, and Saturn commitment or pressure. Full synastry looks at several contacts together.
KEEP EXPLORING
See your Big Three, planets and chart basics.
Try it → FREE TOOL Rising SignFind your Ascendant and your first-impression style.
Try it → FREE TOOL Moon SignDiscover your emotional nature and what feels safe.
Try it → FREE TOOL Venus SignUnderstand your love style, attraction and affection.
Try it →THE CALCULATOR IS THE START
Create your free Staris profile to explore the strongest synastry aspects, recurring triggers and relationship questions with your own birth chart saved as context.
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