Zodiac compatibility, by birth chart (not just Sun signs)

What is zodiac compatibility, really?

When people ask whether two signs are compatible, they usually mean Sun signs: Leo with Scorpio, Capricorn with Cancer. That question has a real answer, and we give it below for all twelve signs. But the Sun is one placement out of roughly a dozen that matter in a relationship, and it is not even the most important one for day-to-day closeness. That job belongs to the Moon (how you feel safe), Venus (how you love and what you find beautiful), Mars (desire and how you fight) and Saturn (what holds when the honeymoon ends).

Astrology compatibility done properly is called synastry: laying one birth chart over another and reading the aspects between them and the houses each person's planets fall into. Two Sun signs that square each other can share a Moon sign and feel like home to one another. Two signs that trine can have Venus opposite Saturn and feel quietly judged for years. The Sun-sign tables are a first filter. Synastry is the actual reading. If you want the mechanics, the synastry guide walks through every aspect and overlay; if you want a number now, the birth chart compatibility calculator gives you one in a few seconds.

How AstraLink scores compatibility

Our compatibility engine uses the tropical zodiac, Placidus houses and ephemeris-grade positions, the same setup as the natal chart in the app. It compares the two charts on four dimensions and then combines them into one score. Every dimension is shown separately, because a couple with high love and low communication needs different advice from a couple with the opposite profile.

Love looks at Venus and Mars in both charts (Venus–Mars, Venus–Venus, Mars–Mars), Sun–Venus, Moon–Venus and the 5th and 7th house overlays. This is attraction, affection, romance and whether you want the same kind of relationship.

Communication weighs Mercury contacts, Moon–Mercury, Sun–Mercury and the 3rd house. It answers whether you can actually talk to each other, especially when it matters.

Friction counts the hard aspects: squares and oppositions from Mars, Saturn, Uranus, Pluto and Lilith to the other person's Sun, Moon, Venus or Ascendant, plus 12th house overlays. Friction is not a verdict. Some is necessary; too much is exhausting.

Growth measures Sun–Moon harmony (the classic marriage aspect), Saturn contacts that stabilise rather than restrict, Jupiter to personal planets, and connections to the lunar nodes, which astrologers read as the sense of a shared direction.

The result is a percentage with a written reason for every contributing aspect. A 68% is not a fail and a 90% is not a guarantee; it is a map of where the relationship will be easy and where it will ask something of you. Chart-based dating in the app works the same way: instead of swiping, you see people whose charts fit yours and why. You can join early access to be in the first matching wave.

Sun-sign compatibility vs full-chart compatibility

Sun-sign compatibility works on two ideas, and both are useful shortcuts.

Elements. Fire (Aries, Leo, Sagittarius) and air (Gemini, Libra, Aquarius) feed each other: air fans fire, fire warms air. Earth (Taurus, Virgo, Capricorn) and water (Cancer, Scorpio, Pisces) nourish each other. Same-element pairings feel familiar. Fire with water and earth with air are the classic mismatches: not impossible, but they run on different fuel.

Modalities. Cardinal signs (Aries, Cancer, Libra, Capricorn) start things; fixed signs (Taurus, Leo, Scorpio, Aquarius) sustain them; mutable signs (Gemini, Virgo, Sagittarius, Pisces) adapt them. Two signs of the same modality are always square or opposite each other, which means they push in ways the other feels. Two fixed signs are the most stubborn combination in the zodiac, which is exactly why Leo and Scorpio is such a searched pairing.

Full-chart compatibility keeps those rules but applies them to the placements that matter for each question. Your Sun sign says who you are becoming. Your Moon sign says what you need at 11 p.m. when the day went badly. Your Venus sign says how you show love and what you read as love. Your Mars sign says what turns you on and how you argue. Your 7th house says who you keep attracting. When those four line up between two people, Sun-sign friction becomes a spark instead of a wall. When they do not, even a textbook trine can feel flat.

Best and worst matches for every zodiac sign

These are Sun-sign reads: the elements and modalities, the traditional trines and sextiles, and the pairings that consistently need the most work. Use them as a first filter, then check the whole chart. "Trickiest" never means "do not date"; it means "expect this specific tension".

Aries (Mar 21 – Apr 19)

Best with Leo and Sagittarius (fire trine: same pace, no sulking), Gemini and Aquarius (air keeps Aries curious). Trickiest with Cancer and Capricorn, the cardinal squares, where Aries's directness reads as carelessness. Aries needs a partner who can hold their own in a fight and forget it by dinner.

Taurus (Apr 20 – May 20)

Best with Virgo and Capricorn (earth trine: shared values around money, home, loyalty), Cancer and Pisces (water softens Taurus without rushing it). Trickiest with Leo and Aquarius, the fixed squares: three signs that dig in and wait for the other to move first. Taurus needs consistency and physical affection more than words.

Gemini (May 21 – Jun 20)

Best with Libra and Aquarius (air trine: conversation as foreplay), Aries and Leo (fire gives the ideas a body). Trickiest with Virgo and Pisces, the mutable squares, where Gemini's lightness is read as not caring. Gemini needs mental novelty and a partner who does not confuse silence with depth.

Cancer (Jun 21 – Jul 22)

Best with Scorpio and Pisces (water trine: unspoken understanding), Taurus and Virgo (earth makes the feelings safe). Trickiest with Aries and Libra, the cardinal squares, where Cancer's moods meet Aries's impatience or Libra's detachment. Cancer needs to feel chosen, repeatedly.

Leo (Jul 23 – Aug 22)

Best with Aries and Sagittarius (fire trine: generous, playful, loud), Gemini and Libra (air adores Leo and Leo needs adoring). Trickiest with Taurus and Scorpio, the fixed squares: pride against possessiveness, warmth against secrecy. Leo needs appreciation out loud and a partner who is proud to be seen with them.

Virgo (Aug 23 – Sep 22)

Best with Taurus and Capricorn (earth trine: competence is attractive), Cancer and Scorpio (water gives Virgo permission to feel). Trickiest with Gemini and Sagittarius, the mutable squares, where Virgo's precision meets scattered or careless energy. Virgo needs to be useful to someone who notices.

Libra (Sep 23 – Oct 22)

Best with Gemini and Aquarius (air trine: ideas, aesthetics, fairness), Leo and Sagittarius (fire gives Libra decisiveness by proxy). Trickiest with Cancer and Capricorn, the cardinal squares, where Libra's diplomacy reads as evasion. Libra needs harmony and a partner who will still say the hard thing kindly.

Scorpio (Oct 23 – Nov 21)

Best with Cancer and Pisces (water trine: depth without explanation), Virgo and Capricorn (earth gives Scorpio somewhere solid to land). Trickiest with Leo and Aquarius, the fixed squares: control against pride, intensity against distance. Scorpio needs total honesty and total privacy at the same time. Our dating a Scorpio and how to attract a Scorpio guides cover the specifics.

Sagittarius (Nov 22 – Dec 21)

Best with Aries and Leo (fire trine: adventure and big feelings), Libra and Aquarius (air keeps the philosophy flowing). Trickiest with Virgo and Pisces, the mutable squares, where Sagittarius's bluntness lands on sensitive ground. Sagittarius needs freedom and a partner who says yes to the trip.

Capricorn (Dec 22 – Jan 19)

Best with Taurus and Virgo (earth trine: building something together), Scorpio and Pisces (water reaches the part of Capricorn that is not working). Trickiest with Aries and Libra, the cardinal squares, where Capricorn's caution reads as coldness. Capricorn compatibility improves dramatically when the other person respects their timeline; Capricorn needs to be trusted with the long game.

Aquarius (Jan 20 – Feb 18)

Best with Gemini and Libra (air trine: friendship first, always), Aries and Sagittarius (fire gives the ideals a pulse). Trickiest with Taurus and Scorpio, the fixed squares, where Aquarius's need for space reads as rejection. Aquarius needs a partner who is also a person in their own right.

Pisces (Feb 19 – Mar 20)

Best with Cancer and Scorpio (water trine: intuition meets intuition), Taurus and Capricorn (earth gives Pisces a shore). Trickiest with Gemini and Sagittarius, the mutable squares, where Pisces's sensitivity meets restlessness. Pisces needs tenderness and a partner who does not exploit how much they give.

The placements that decide more than your Sun sign

Moon–Moon. When two Moons are in the same element or in trine, you decompress the same way. When they square, one person wants to talk it out while the other wants to be left alone; nobody is wrong, and both feel abandoned.

Venus–Mars. The classic attraction aspect. Venus conjunct or trine the other person's Mars is the pull you cannot explain to friends. Venus square Mars is also attraction, with more arguing.

Sun–Moon. One person's Sun conjunct or trine the other's Moon is the oldest marriage indicator in the books: one shines, the other feels it, and it feels like being understood.

Saturn contacts. Saturn conjunct a partner's Sun, Moon or Venus is the glue: it makes the relationship feel serious and lasting. In hard aspect, it can also feel like being graded. The 7th house shows what kind of partner you are drawn to and, in synastry, which of their planets land there.

The lunar nodes. Planets on a partner's North Node feel like destiny; planets on the South Node feel like familiarity, sometimes too much. With the North Node moving into Aquarius and the South Node into Leo from July 2026, the coming year asks fixed-sign couples in particular to renegotiate the balance between me and us.

Compatibility in the AstraLink app

On this site the calculator works from birth dates and gives a Sun/Moon/Venus read. In the app, you enter a partner's full birth data (date, time, place) and get an AI synastry reading: every significant aspect between the charts, the house overlays, the four dimension scores and a plain-English summary of what will be easy and what will need work. Cosmic Dating uses the same engine to match you with people whose charts fit yours, and shows the reasons before you ever say hello. Unlimited compatibility and Cosmic Dating are part of Premium; early-access members get founding-member pricing.

If you want to learn to read this yourself, start with Venus in astrology and the square aspect, then move to the full synastry guide.