Compatibility by birth date
Enter two birth dates and the calculator shows the links between two charts in Human Design, BaZi and astrology. Time and place are optional, and there is nothing to pay and no sign-up.
What this calculator counts
The calculator takes two birth dates and reads each person through three systems at once: Human Design, BaZi and Western astrology. Then it puts the two charts side by side and looks for links between them. No AI writes the result: code picks every line from the calculation, so the same dates always give the same answer.
In Human Design it looks at the 36 channels. A channel joins two gates, that is two points on the chart's diagram; which gates a person has depends on the date and hour of birth. If one person has one gate and the other person has the second, the channel switches on only when the two are together. This is called an electromagnetic link, and the page labels it "attraction". A channel can also be whole in both people (a shared channel), whole in one and half in the other (giving way), or whole in one and absent in the other (leading).
In BaZi the key for a pair is the two day masters, the element of each person's birth day. The elements are linked by two cycles: one feeds another (Water feeds Wood, Wood feeds Fire) or restrains it (Water restrains Fire). The calculator also checks whether the two people's birth-day signs form a union or clash (in BaZi every day has two signs: a stem and a branch).
In astrology it compares the two Suns, Moons and Ascendants. An aspect between them, a trine or a square for example, is a link between the charts. Astrologers call this comparison synastry.
How to read the percentage
The percentage shows where the pair stands by number of links among random pairs. For comparison we counted the links in forty thousand pairs born between 1950 and 2005, and the percentage is the share of them that have fewer links. It also picks one of five levels: below 20% is a very weak link, then weak, average and strong, and from 80% up a very strong link. Without birth times fewer links are visible, so pairs with unknown times are compared with pairs like them.
Many links mean the two touch each other strongly, and that can be warm and can be hard. If there are few links, each lives their own life, and the pair has to grow closer by their own decision.
Common questions about compatibility
Can I check compatibility without the birth time?
Yes, two dates are enough. Then the calculator does not show the Human Design type, profile, authority or the Ascendant: they change within a single day, and showing them would be a guess. It only uses the channels that hold for the whole birth day and says that the rest depend on the hour. If you know the time, the place is needed too: without it the time cannot be turned into the real position of the sky.
What is an electromagnetic channel?
It is a Human Design channel with one half in one person and the other half in the other. Neither has it alone, and it switches on by itself when they are together. That is why these channels usually describe the pull in a pair: the two get something neither has separately. The channel names on the page lead to their descriptions.
How does BaZi look at a couple?
BaZi compares the day masters. If one person's element feeds the other's, the first gives support and the second grows. If it restrains, the first sets a frame and the second learns to live in it. If the element is the same, the two understand each other easily. The day master depends only on the date, but the in BaZi a new day starts at 23:00, so for someone born between 23:00 and midnight the day master without a time may be the neighbouring one.
How is this different from zodiac sign compatibility?
Sign compatibility only looks at the Sun: Aries with Libra, Cancer with Scorpio. Here the Sun is one point among many. The calculator also checks the Moon and the Ascendant, and Human Design and BaZi give links that the zodiac does not have at all. So two people with "incompatible" signs can turn out to be a pair with a strong pull, and the other way round.
Is the compatibility check really free?
Yes. Both charts, the links between them and the percentage are calculated for free, with no account and no email. The paid product is the full portrait of one person, and its price is on the pricing page.
Can I see my own chart, not only the pair?
Yes, from the same birth data. The Human Design calculator shows your type and draws your bodygraph, the Human Design diagram of nine centres; the birth chart calculator shows your Rising and the sign of every planet, and the BaZi calculator shows your four pillars. All three are free and need no sign-up.
What happens to the second person's data?
Nothing is kept. The dates go to the server only for the calculation and are not written to any database, and the names never reach the server at all: your browser puts them into the text. No account or email is needed.