All relationship types
Partner compatibility

Two birthdays, one honest look at the pairing

The classic love compatibility check - a score, a category breakdown and a card you can send to the person it is about.

No astrology APILocal and deterministicMobile friendly
Person A
Person B

Ready to compare two birth dates?

Enter two birthdays and a relationship type to get an easy-to-read compatibility report with printable details.

This is the compatibility question everybody asks first, and the one the internet has answered more times than any other. What is different here is what surrounds it: this calculator was built for a family tree site, so partner compatibility sits alongside the in-law, sibling, parent-child and grandparent versions of the same question - which is where relationships actually get lived.

The partner score carries no modifier. It is the baseline the other relationship types are adjusted against, drawn from the elemental relationship between the two signs and then broken into communication, emotional connection, family harmony and support and trust.

Family harmony is the category worth pausing on, and the one most love-compatibility tools leave out entirely. Long relationships are rarely decided by whether two people enjoy each other's company. They are decided by holidays, by whose parents get Christmas, by how each person behaves in somebody else's house. Two signs can be excellent as a couple and difficult as an addition to a family, and the score separates those.

If the result is interesting, the more useful follow-up is not another couple check. It is running your partner against your mother, or your sibling, or your child. That is where a compatibility score stops being entertainment and starts explaining something you had already noticed at a dinner table.

As with every report here, this is for cultural interest and reflection. It is not advice, and it is not a reason to do or not do anything.

Each relationship type is scored differently, because each one carries a different amount of shared history.

Frequently asked questions

The calculator uses a local zodiac engine and deterministic compatibility rules so the same dates always produce the same report.

Is this the same as a love calculator?+

It is the same question, answered from zodiac signs and elemental relationships rather than from names. Unlike most love calculators, the same two birth dates always produce the same result.

Do you need birth time or place?+

No. This calculator uses date of birth only, which is all that is needed for a sun sign. Nothing here requires a birth chart or an ephemeris.

What should I do with a low score?+

Read the challenges section and nothing else. A low score describes a temperament gap, not a verdict, and this report is explicitly not advice about any relationship decision.

Can I check my partner against my family?+

That is the more interesting use of this tool. The in-law and parent-child pages run the same calculation with the modifiers those relationships actually need.