WESTERN SYNASTRY · TWO BIRTH CHARTS

Compare two birth charts

Enter both sets of birth details. The calculator identifies the cross-chart aspects involving the Sun, Moon, Venus, Mars and other planets, then explains their relationship themes. It uses the calculated charts rather than a generic horoscope and does not use AI.

You

First name

Middle name (optional)

Last name

Date of birth

Time of birth

I don't know my exact birth time (we'll use noon as a fallback)

Birth place

Your partnerName

Date of birth

Time of birth

Birth time unknown (we’ll use noon as a fallback)

Birth place

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How Western synastry works

Synastry compares two birth charts by calculating the aspects between their planets. Trines and sextiles are usually read as supportive, squares and oppositions as sources of tension, and conjunctions as intensifying the planets involved. This page calculates the actual aspects between the two charts and does not use a generic horoscope or AI.

The five Major aspects

Conjunction

A conjunction places the two bodies on the same degree, so their energies merge and amplify one another. In synastry it is the most intense contact — neither soft nor hard on its own. It intensifies whatever the two planets signify, for better and for more.

Sextile

A sextile (60°) is an easy, opportunity-flavoured contact. The two bodies cooperate when either person reaches for it — supportive rather than effortless, a door that opens with a little initiative.

Square

A square (90°) is the classic friction aspect: the two bodies pull in directions that don't naturally agree, creating tension that asks to be worked with. Handled consciously it is the engine of growth in a relationship, not a verdict against it.

Trine

A trine (120°) is the most harmonious contact — the two bodies share an element and flow together with little effort. It brings ease and natural understanding, the parts of a relationship that simply work.

Opposition

An opposition (180°) sets the two bodies face to face. It carries both attraction and tension — each person meets in the other something they lack, which can be magnetic or polarising depending on how the balance is held.

What each body governs

Sun

Sun — the core self, identity, and vitality each person brings.

Moon

Moon — the emotional nature: how each person feels, seeks comfort, and nurtures.

Mercury

Mercury — the mind and communication: how each person thinks and talks.

Venus

Venus — affection, attraction, and values: how each person loves and what they find beautiful.

Mars

Mars — drive, passion, and assertion: how each person acts and desires.

Jupiter

Jupiter — growth, generosity, and faith: where each person expands and gives.

Saturn

Saturn — structure, commitment, and limits: where each person is serious and durable.

Uranus

Uranus — freedom, surprise, and change: where each person breaks from routine.

Neptune

Neptune — imagination, idealism, and longing: where each person dreams or softens boundaries.

Pluto

Pluto — depth, power, and transformation: where each person is intense and unguarded.

Ascendant

Ascendant — the self each person presents and how they first meet the world.

Midheaven

Midheaven — direction, vocation, and public standing: where each person is heading.