Synastry Calculator
Enter two sets of birth details to compare the charts. You get both big threes (Sun, Moon and rising) side by side, plus the key aspects between the two people, computed from real astronomy in your browser.
Person A
Person B
Aspects between the two charts
Angles measured between one person's planet and the other's, within an 8 degree orb. Conjunctions blend the two energies, trines and sextiles flow easily, squares and oppositions create tension and charge.
Overall note
How this works. Both charts are calculated from real astronomy (the same engine used inside the Alya app), using the tropical zodiac and whole-sign houses. Each aspect is the angle between one person's planet and the other's: the tool takes the shorter distance around the wheel and marks it when it lands within 8 degrees of a conjunction, sextile, square, trine or opposition. Your details are used only in your browser to compute the two charts. The birth place lookup sends only the city name you type to a geocoding service to find its coordinates.
For entertainment and reflection. Astrology is a symbolic tradition, not a science. This comparison is grounded in real planetary positions, but its meaning is interpretive. It is a starting point for a conversation, not a verdict on any relationship, and it is not medical, psychological, legal or financial advice.