Birthday Compatibility, the Korean Way: How Saju Compares Two Birth Dates (Gunghap)
Most birthday compatibility tests add up digits or compare sun signs. Korea has used something far older for centuries: gunghap (궁합), which compares two people's full birth charts. Here is how birthday compatibility works in Korean saju — and what it can and cannot tell you.
Your Birthday Is a Chart, Not a Number
In saju your birth date and time become four pillars — year, month, day and hour — each written as a heavenly stem over an earthly branch. That is eight characters, and each carries one of the five elements: Wood, Fire, Earth, Metal or Water.
Birthday compatibility in saju means comparing two of these charts. Your birth date alone gives you six of the eight characters, so even without birth times you can see a lot.
Step 1: Compare the Day Masters
The stem of the day you were born is your Day Master — the part of the chart that is you. Gunghap starts by asking how the two Day Masters relate through the five-element cycles.
If one Day Master's element feeds the other's (Wood feeds Fire, Fire makes Earth, Earth holds Metal, Metal carries Water, Water nourishes Wood), support tends to flow easily. If one controls the other (Wood parts Earth, Earth dams Water, Water puts out Fire, Fire melts Metal, Metal cuts Wood), there is spark, structure — and sometimes pressure.
Check your birthday compatibility
Both Day Masters, your match score and what your charts say — times and places optional. No sign-up.
Step 2: Do You Fill Each Other's Gaps?
Next, saju looks at element balance. If your chart is short on Water and your partner's is full of it, you may feel calmer and clearer around them — and they may value the warmth or drive you bring.
This is one reason opposites attract in saju terms: the element your chart needs most is often the one you are drawn to in another person.
Step 3: Harmonies and Clashes Between Branches
The earthly branches — the zodiac animals in each pillar — can combine or clash. Three-harmony groups (such as Rat, Dragon and Monkey) and six-harmony pairs (such as Rat and Ox) bring ease; opposite branches (such as Rat and Horse) bring movement and friction.
The day branch matters most here. In Korean saju it is called the spouse palace (배우자궁): a harmony between two people's day branches is read as an easy home rhythm, a clash as a lively, sometimes restless one.
What Birthday Compatibility Can — and Can't — Tell You
Saju compatibility describes tendencies: where things flow easily between two people and where a little extra patience helps. It does not predict how a relationship will end, and it never decides what another person will feel or choose.
Many Korean couples check gunghap out of curiosity, the way others read horoscopes together. Treat it as a conversation starter about how you each communicate, rest and handle stress.
Check your birthday compatibility
Both Day Masters, your match score and what your charts say — times and places optional. No sign-up.
Questions people ask
Can I check compatibility with just two birthdays?
Yes. Two birth dates give you both Day Masters and six of eight characters each. Birth times and places make the hour pillars and the exact solar time more precise.
Is a low compatibility score bad?
No. A challenging match shows where understanding is needed; plenty of happy couples have clashes in their charts. Saju describes tendencies, not outcomes.
Is gunghap the same as zodiac compatibility?
Zodiac compatibility compares only the birth-year animals. Gunghap compares the whole charts, with the Day Masters at the center.
Why do Koreans check gunghap?
Traditionally families compared charts before weddings. Today it is mostly a fun, reflective look at how two people fit — often done by couples together.
More guides
Read your whole chart
Your day pillar is one of eight characters. See all four pillars, your five elements and your 2027 — the first chapters are free.