How to Read a Synastry Chart

Check both birth dates, times, and places before reading the chart. These details set the positions used in the comparison, and the birth time matters for the Ascendant, Midheaven, and houses. A synastry chart compares two birth charts to show where their planets and points meet. An aspect is a geometric link between two positions, such as a trine or square. These terms help you name what the chart displays without turning it into a verdict.

The sample couple, two invented people, Person A and Person B, both have a known birth time. That lets the example include Ascendants and house overlays. If either birth time is unknown, the angles and houses are removed from the reading because their positions cannot be set reliably. The planet contacts can still be read, but the chart gives less detail about how each person experiences the other's presence in daily life.

An orb is the gap between two points and the exact angle of an aspect; a smaller orb makes a closer, stronger link. Begin with the personal planets, which include the Sun, Moon, Venus, and Mars, then notice how close each contact is. In the sample, Person A's Mars trine Person B's Moon has an orb of 0.22 degrees, within an allowed orb of 7 degrees. It is the closest contact in the list, so it is a clear place to begin.

Next, Person A's Venus opposite Person B's Sun has an orb of 2.47 degrees, within an allowed orb of 7 degrees. Person A's Ascendant square Person B's Mars has an orb of 0.6 degrees, within an allowed orb of 5.5 degrees. These are close links too, though one involves the Ascendant. The calculator's allowed orb shows which links count in this chart; the smaller orb tells you which counted links are closest.

Say whose planet, which aspect, and whose planet, in that order. Person A's Mars trine Person B's Moon is not the same sentence as Person A's Moon trine Person B's Mars. The planets belong to different people in each reading, so the order shows who brings which quality and who meets it. The direction does not make one person or side stronger. Keeping the names attached to the planets stops a long table from blurring into a list of aspect names.

For the sample contact, A brings Mars: direct action, initiative, and a way of pursuing what matters. B brings the Moon: emotional reactions and a need for comfort. The trine describes an easy link between these parts, so A's drive can sit naturally beside B's feelings. In an everyday moment, A may take the lead while B responds readily. That is a theme to notice, not a rule for how either person behaves.

The sample has 31 contacts in total: 12 harmonious and 19 challenging. The lopsided count says little on its own. A table may show many links because it includes several kinds of planets and points, and the count does not explain how people handle them. Squares and oppositions describe friction, such as different timing or clashing preferences. Trines and sextiles describe ease, but easy patterns can be taken for granted when no one makes an effort to notice them.

Neither harmonious nor challenging contacts make a relationship good or bad. Read each contact for the theme it brings, then consider how it sits beside the others. A square between personal planets can describe a recurring difference that people learn to name. A trine can describe a point of easy understanding that rarely gets discussed. The labels sort the contacts by style; they do not measure the care, respect, or choices between two people.

A house overlay is one person's planet falling in a house of the other person's chart. Read Person A's planets in Person B's houses, then reverse direction and read Person B's planets in Person A's houses. In the sample, A's Sun and Venus fall in B's 12th house, while A's Moon falls in B's 4th house. These placements suggest areas of life where B may notice A's presence, but they do not describe the same experience from A's side.

In the other direction, B's Venus falls in A's 7th house and B's Mars falls in A's 3rd house. The 7th house brings attention to one-to-one relating, while the 3rd house brings attention to conversation and everyday exchanges. B's Venus there is not interchangeable with A's Venus in B's 12th house. The two directions describe different viewpoints. Read both, and keep each person's planet attached to the receiving house.

The composite chart is made from the midpoints of the two birth charts and offers a picture of the two people together. Read it after the contacts and house overlays, so its themes have context. A composite placement can describe what becomes prominent when the two people meet, such as how they handle shared plans or present themselves together. It adds a view of the relationship as a unit; it does not replace the details of how one person's planets meet the other's.

Treat the reading as a set of themes to talk about, not a verdict on the relationship. A few close contacts can matter more in conversation than a long list of loose links. What people do with a contact matters more than the contact itself: one person can name a difference, listen, and adjust, while another moment brings the same difference into sharper view. The chart describes patterns people may recognize; their choices give those patterns their place in daily life.