Free Astrology Calculator
Birth Chart Compatibility Calculator
Compare two whole birth charts, beyond Sun signs. See how your Sun, Moon, Mercury, Venus, Mars and Rising signs relate to theirs, how the two charts balance by element, and the closest aspects between them.
Compatibility Beyond Sun Signs
Sun sign compatibility compares one placement from each person. It is a good place to start and a poor place to stop. A Scorpio and an Aries may find their Suns hard to reconcile and still share a Moon sign, so that home life feels easy, or have one person's Venus in the same sign as the other's Mars, which is a classic picture of attraction. Comparing whole charts shows which layers of the relationship come naturally and which ask for work.
What This Calculator Compares
- Sun: identity and purpose, what each person is here to become.
- Moon: emotional needs and the daily texture of living close.
- Mercury: how each person thinks, talks and listens.
- Venus and Mars: how each person loves and how each wants, compared within each chart and across them.
- Rising sign: first impressions and how each person meets the world. It needs a birth time and place.
- Elements and aspects: how the two charts balance fire, earth, air and water, and the closest angles between their planets.
How Two Signs Relate
Every comparison here rests on one idea: the distance between two signs around the zodiac describes how they meet. Signs of the same element sit four apart, signs of the same mode three or six apart.
| Distance | Example | How They Meet |
|---|---|---|
| Same Sign | Leo and Leo | They share a sign, so they speak the same language and can share the same blind spots. |
| Neighbors | Leo and Virgo | They sit next to each other, different in temperament, with a lot to learn from the contrast. |
| Sextile | Leo and Libra | They are two signs apart, in friendly elements, so the exchange tends to feel easy. |
| Square | Leo and Scorpio | They are three signs apart, in elements that work differently, so they meet with friction that asks for adjustment. |
| Trine | Leo and Sagittarius | They are four signs apart, in the same element, so they tend to understand each other quickly. |
| Quincunx | Leo and Capricorn | They are five signs apart, with little in common by element or mode, so they need conscious translation. |
| Opposite | Leo and Aquarius | They sit opposite each other, drawn to each other's missing half and asked to find a balance. |
Reading the Result Without a Score
The calculator does not grade the relationship. Easy pairings can feel comfortable and stay shallow; hard ones are often where two people learn the most about themselves. Read each comparison as a description, notice which ones you recognize, and ask what the friction and the ease each invite you to practice. For the aspects between every pair of planets, use the synastry chart calculator; for the relationship as one chart, the composite chart calculator.
Sun Sign Compatibility Guides
Each guide reads one pairing of Sun signs in depth: the core dynamic, where friction comes from, and how the two can grow.
Aries
Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, Pisces
Taurus
Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, Pisces
Gemini
Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, Pisces
Cancer
Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, Pisces
Leo
Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, Pisces
Virgo
Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, Pisces
Libra
Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, Pisces
Scorpio
Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, Pisces
Sagittarius
Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius
Capricorn
Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, Pisces
Aquarius
Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, Pisces
Pisces
Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Capricorn, Aquarius, Pisces
Compatibility Questions
How Do You Check Birth Chart Compatibility?
Compare the same placements in both charts: Sun with Sun, Moon with Moon, Venus with Venus, Mars with Mars and Rising with Rising, then each person's Venus with the other's Mars. Then look at the aspects between the charts, which is synastry. This calculator does both from two sets of birth details.
Is Sun Sign Compatibility Accurate?
Sun signs describe one layer: each person's core sense of self. Two people with a hard Sun sign pairing can share Moon signs or close Venus and Mars contacts that change how the relationship feels. That is why astrologers compare whole charts, and why our sign pair guides end with what to look at beyond the Sun.
Which Placements Matter Most for Compatibility?
The Moon for emotional comfort and daily life together, Venus for how each person loves and what they enjoy, Mars for desire and how conflict is handled, Mercury for conversation, and the Sun for identity and purpose. The Ascendant colors first impressions and how each person meets the world.
Do I Need Both Birth Times?
No. Sun, Mercury, Venus and Mars signs come from the date alone, as long as the planet did not change sign that day. The Moon changes sign every two to three days, so without a time it may be uncertain, and the Ascendant needs the time and place. The calculator shows only the comparisons the details can support.
Does This Calculator Give a Compatibility Percentage?
No. A percentage adds contacts together as if they all weighed the same and as if friction were always bad. The calculator shows how each pair of signs relates and the closest aspects between the charts, so you can see what the relationship is made of and judge it yourselves.
What Does It Mean When Two Signs Are Square or Opposite?
Signs three apart (square) belong to elements that work differently, such as fire and water, so they meet with friction that asks each person to adjust. Signs six apart (opposite) look at the same theme from two ends, which often reads as strong attraction and a need for balance. Neither is a bad sign; both describe where two people have work and growth to do together.
Is Birth Chart Compatibility Only for Couples?
No. The same comparisons describe friends, family members, business partners and colleagues. Venus and Mars contacts read as attraction in a romance and as shared taste and shared drive in a friendship or a working partnership.