Compare two birth charts
See how two charts meet: Sun, Moon, Venus, Mars and Rising, explained in plain English. For partners, crushes, friends or family. No score, no sign-up, and nothing leaves your device.
How we compare two charts
We calculate both birth charts with the same accurate astronomy as our birth chart tool, then look at how the signs relate. Astrologers call this synastry. Signs that share an element (fire, earth, air or water) are traditionally read as an easy fit. Signs opposite each other are read as an attraction of opposites. Signs that share a mode but not an element, called a square, are read as friction that takes some negotiation.
We give the most weight to the links astrologers usually look at first: one person's Sun with the other's Moon, and one person's Venus with the other's Mars. We compare by sign rather than exact degree, so it still works without birth times.
Common questions
How does birth chart compatibility work?
Astrologers compare where the planets were for two people, a practice called synastry. We look at how your Sun, Moon, Venus, Mars and Rising signs relate to each other: whether they share an element, sit opposite, or clash by mode. It’s a symbolic tradition, not a science, so read it as conversation starters rather than a verdict.
Why don’t you give a compatibility percentage?
Because no honest method can produce one. A percentage looks scientific, but it’s just a made-up weighting of symbolic links, and it can make people worry about a good relationship or ignore real problems. We show how your charts relate and leave the judging to you.
Is Sun sign compatibility enough?
It’s a start, but it’s one link out of many. Astrologers usually give as much weight to the Moon, which describes emotional needs, and to Venus and Mars, which describe affection and attraction. Two people with “incompatible” Sun signs often have easy links elsewhere.
Do we need both birth times?
No. Without birth times you still get Sun, Venus and Mars links, and usually the Moon too. Rising signs need both birth times. If the Moon changed sign on someone’s birthday, we tell you which links depend on the time instead of guessing.
Can astrology say if a relationship will last?
No. Nothing in a chart can predict that, and we’d be wary of anyone who claims otherwise. What lasts tends to depend on respect, communication and the choices two people make every day. Astrology can be a fun way to talk about those things together.
Is it private?
Yes. Both charts are calculated in your browser. Neither person’s birth details or names are sent to us or saved anywhere.