Two dates or a whole family
Compare birthdays
Put in two or more birth dates and see what they share — sign, Chinese animal, stone, flower, the weekday and the moon they were born under — and what lies between them: the days apart, the years their birthdays fall on the same weekday, the day their ages add up to a round number.
The comparison needs JavaScript. Without it every date still has its own page, with its sign, stone, flower and the weekday it fell on in every year: pick one from the index.
What is compared
Two kinds of thing, kept apart. The first is arithmetic on the calendar: how many days separate two births, which weekday each birthday falls on in a given year, how old each of you was when the other was born, and when your ages added together reach the next hundred. Those are facts, and they are exact to the day.
The second is tradition, worked out the same way the birthday calculator works it out: the star sign from the moment the sun changed sign, the Chinese animal from the real lunar new year, the birthstone and birth flower of each month, the generation, the life path number, the tarot birth card and the phase of the moon. Where two of you share one, the table shades it.
Why there is no compatibility score
A percentage would look like a measurement, and nothing in two dates can measure how two people get on. Sites that print one are adding numbers that stand for nothing. This page shows what the dates have in common and leaves the meaning to you; what each tradition says about a sign or an animal is on that sign's or animal's own page, attributed to the tradition that says it.
The dates you put in stay in your browser. Copy link makes an address that carries the dates after a # sign, which a browser never sends to a server; the names never go into it.