Which zodiac signs are compatible? Sign comparisons and synastry explained

In traditional astrology, signs of the same element are considered especially harmonious (a trine, such as Leo and Sagittarius), alongside fire with air and earth with water (a sextile). Squares (three signs apart, such as Taurus and Leo) and opposite signs (an opposition, such as Aries and Libra) suggest tension. This only compares Sun signs. Full synastry compares two complete birth charts by degree, including the Moon, Venus, Mars, ascendant and houses. It needs both people's birth times and places. No table can predict whether a relationship or situationship will work.

Compatibility check: Sun, Venus and Mars from two birth dates (free, runs in your browser)

Enter two birth dates between 1935 and 2012. The check compares Sun, Venus and Mars signs across both charts. Nothing is stored or sent.

How zodiac compatibility charts work

Most compatibility charts follow the same rule: they count the signs between two zodiac signs and interpret that distance as an aspect. Each sign has an element (fire, earth, air, water) and a modality (cardinal, fixed, mutable). The distance determines what two signs share:

Distance	Name	In common	Traditional interpretation
0	Same sign	Everything	Instant recognition, shared blind spots
1	Semi-sextile (neighbouring signs)	Nothing	Different without clashing
2	Sextile	Compatible elements	Stimulating, straightforward
3	Square	Modality	Friction, different pace, a spark
4	Trine	Element	Ease, a similar rhythm
5	Quincunx	Nothing	Slightly out of step, constant adjustment
6	Opposition	Modality, axis	Complementary attraction, a tug of war

For two randomly chosen Sun signs, the chance of sharing a sign is 1 in 12; the chance of a trine is 1 in 6, as is the chance of a square. Each sign therefore has more challenging or unfamiliar matches than easy ones.

Zodiac compatibility chart

Sign	Element, modality	Same element (trine)	Sextile	Square	Opposite sign
Aries	fire, cardinal	Leo, Sagittarius	Gemini, Aquarius	Cancer, Capricorn	Libra
Taurus	earth, fixed	Virgo, Capricorn	Cancer, Pisces	Leo, Aquarius	Scorpio
Gemini	air, mutable	Libra, Aquarius	Leo, Aries	Virgo, Pisces	Sagittarius
Cancer	water, cardinal	Scorpio, Pisces	Virgo, Taurus	Libra, Aries	Capricorn
Leo	fire, fixed	Sagittarius, Aries	Libra, Gemini	Scorpio, Taurus	Aquarius
Virgo	earth, mutable	Capricorn, Taurus	Scorpio, Cancer	Sagittarius, Gemini	Pisces
Libra	air, cardinal	Aquarius, Gemini	Sagittarius, Leo	Capricorn, Cancer	Aries
Scorpio	water, fixed	Pisces, Cancer	Capricorn, Virgo	Aquarius, Leo	Taurus
Sagittarius	fire, mutable	Aries, Leo	Aquarius, Libra	Pisces, Virgo	Gemini
Capricorn	earth, cardinal	Taurus, Virgo	Pisces, Scorpio	Aries, Libra	Cancer
Aquarius	air, fixed	Gemini, Libra	Aries, Sagittarius	Taurus, Scorpio	Leo
Pisces	water, mutable	Cancer, Scorpio	Taurus, Capricorn	Gemini, Sagittarius	Virgo

For example, Aries and Leo (fire) are traditionally the easiest matches for Sagittarius; Libra and Aquarius (air) are stimulating, Virgo and Pisces bring tension, and Gemini is its opposite.

Why Venus and Mars reveal more than the Sun

In love astrology, Venus describes what attracts you and how you show affection; Mars describes desire and conflict. A connection between one person's Venus and the other's Mars is the classic spark. The check above therefore compares Venus with Venus and Venus with Mars across both charts, as well as the Suns.

Venus stays close to the Sun in the sky: seen from Earth, it never moves more than about 47° away. Your Venus is therefore in your Sun sign or within two signs on either side. Across all birth dates from 1935 to 2012, we counted Venus in the Sun sign for 23.4% of dates, one sign away for 58.6% and two signs away for 18.1%. Comparing only the Sun therefore misses the Venus sign in three out of four cases.

The Moon changes sign roughly every two and a half days; the ascendant changes about every two hours. Neither can be reliably established without a birth time, so the free check leaves them out.

What full synastry involves

Synastry compares two complete birth charts. It uses precise angles between both people's planets, usually allowing a few degrees of tolerance (an orb), rather than counting signs. It also considers which houses in one chart contain the other person's planets. This needs both people's birth dates, times and places. For example, Venus at 29° Leo and Mars at 1° Sagittarius occupy signs that form a trine, but are 92° apart: much closer to an exact square.

The check above compares signs. Our Situationship Horoscope also focuses on your own birth chart rather than calculating synastry. Ask before entering someone else's details: birth details are personal data.

“Are we compatible?” often means a situationship

A situationship is a romantic or sexual connection without the status of a committed relationship. The word was one of four finalists for the Oxford Word of the Year in 2023. On X, people ask whether to message an old situationship. When asked whether matching zodiac signs matter in a relationship, many simply say no: character and personality count.

That fits the astrological perspective: whether a connection stays undefined depends less on the other person's Sun sign than on your own patterns and how you communicate. Traditional situationship signatures include Venus in a mutable sign (Gemini, Virgo, Sagittarius or Pisces, around a third of all birth dates) or tension between Venus and Mars. Venus is also currently retrograde (3 October to 14 November 2026), a period when many revisit old or unresolved connections: Venus retrograde and your ex.

Situationship Horoscope (€4): a personal pattern score based on five traditional signatures in your birth chart, as a PDF and an image for Stories. A reflection of your own patterns.

Find out more →

More on Cosmolytic: all twelve zodiac signs one by one, the four elements and three modalities behind every compatibility table, and why a trine runs more easily than a square.

Frequently asked questions

Which zodiac signs are the best matches?

Traditionally, signs of the same element form a trine: Aries, Leo and Sagittarius (fire), Taurus, Virgo and Capricorn (earth), Gemini, Libra and Aquarius (air), Cancer, Scorpio and Pisces (water). Fire with air and earth with water form sextiles.

Which zodiac signs clash?

Signs in a square, three signs apart with the same modality, are traditionally associated with tension: Aries and Cancer or Taurus and Leo, for example. Opposite signs such as Aries and Libra suggest attraction and conflict. Astrology does not treat this as a reason to rule someone out.

Is zodiac compatibility the same as synastry?

No. Zodiac compatibility compares two Sun signs. Synastry compares two complete birth charts by degree, including all planets, the ascendant and houses. It needs both people's birth times and places.

Can you find your Venus sign from your birth date?

Yes, on most days a birth date is enough to find the Venus sign. You only need the time on days when Venus changes sign. Venus is always in the Sun sign or within two signs of it.

Is there a situationship zodiac sign?

There is no single Sun sign for situationships. Traditional signatures appear in your own birth chart, such as Venus in a mutable sign, Venus aspecting Neptune, or tension between Venus and Mars.

What do I need for a full synastry reading?

Both people's birth dates, birth times as accurately as possible, birthplaces, and the other person's consent to use their details. Without a birth time, the ascendant, houses and sometimes the Moon sign are missing.

Sources

Responsible: Maximilian Stroh, Anonyfox e. K., Hamburg

Dates and any times on this page use Central European Time (CET/CEST).