How do you read two birth charts in synastry?
Learn how to identify cross-chart aspects, work with uncertain birth times and use synastry as a conversation prompt.
Keep track of who owns each placement
Synastry compares positions in two birth charts. A square from one person's Mars to the other's Mercury is a cross-chart aspect; it says nothing about whether either individual has a Mars–Mercury square in their own chart. Start by checking whose planet appears on each side.
Use the information you actually have
Use birth details that the other person is comfortable sharing. When the birth time is unknown, treat houses and angles as uncertain. The Moon also moves enough during a day to make some contacts sensitive to the time. Avoid filling in a guessed time and treating the resulting chart as precise.
Explore a comparison in Synchronicity
Open Synastry, select or enter the two birth profiles and look at one cross-chart aspect alongside the broader relationship themes. If a reading mentions different communication rhythms, ask each other what actually helps when a conversation gets tense. An interpretation cannot measure consent, settle a conflict or decide whether a relationship will work.