BaZi compatibility calculator
In BaZi (八字, the Four Pillars), your core element — what BaZi books call the day master, is the heavenly stem of the day you were born. This calculator compares two whole charts, not just two day masters or two year animals, and shows every reason that moved the score. The score and its reasons are free.
An example with two sample dates
Sample A was born on March 14, 1992: a Yin Earth day master, born in a Monkey year. Sample B was born on September 11, 1989: a Yang Wood day master, born in a Snake year. These are sample dates, not real people, entered without birth times or cities.
Yin Earth 己 and Yang Wood 甲
Monkey and Snake — allies
71out of 100
- +18
Your core elements (己 and 甲) are a classical pairing that combines into Earth — one of the clearest signs of attraction in this system
- +7
Beyond the partner position, 1 more branch pair is in harmony, which helps everyday matters fall into place
- −7
1 branch pair clashes outside the partner position, which usually shows up as mismatched timing rather than anything major
- +10
Your zodiac years (Monkey and Snake) are natural allies
- +9
One of you has Fire, which barely shows in the other's chart, so you fill a gap for each other
The signals below add up to +37, which the scale turns into 71 out of 100.
Compare two birth dates
Only the dates are required. Add a birth time and city for either person and that chart gains its hour pillar, converted to local solar time. The result opens on the home page: your own free chart, with the comparison in the section “Compare with someone in your life”.
The other person’s birth details are used only to calculate this comparison. Birth details travel in the page address, so they can appear in the logs of our hosting provider, Cloudflare: request logs, deleted automatically within 7 days, and sampled security and traffic records, kept for up to 31 days. They are not saved to our database or to any account. Only enter someone’s details if they are comfortable with it.
What the score measures
The score adds up five kinds of signal from the two charts. Each one is a classical relation between stems, branches or elements, and each comes with a fixed number of points:
The two day masters
+18 when the two day stems are one of the five classical stem pairs, such as Jia with Ji. The tradition reads such a pair as attraction; any other two day masters add nothing here.
The two partner positions
+22 / +15 / −22 for the branches of the two day pillars, which BaZi reads as the partner position: +22 for a six-harmony pair, +15 for two branches of the same trine, −22 for a clash. This is the heaviest single signal.
The other branches
+7 / −7 each for every six-harmony pair and every clash between the remaining branches of the two charts (year, month and, when a time is given, hour), counted up to three of each.
The two year animals
+10 / +7 / −10 for the branches of the two year pillars, the popular zodiac check: +10 for allies, +7 for the same trine, −10 for animals in opposition. The year branches also count in the row above.
The five-element balance
+9 each / −5 for each element that one chart shows and the visible stems and branches of the other lack, counted in both directions, and −5 when both charts are heaviest in the same element.
How the points become a score out of 100
The points are added up and placed on a fixed straight-line scale, on which a pair with no signal at all scores 42 out of 100 and every 13 points of signal move the score by 10. The score is then kept between 5 and 95, because the tradition does not treat any two charts as entirely incompatible or as perfect.
The calculation is symmetric, so two people get the same score in either order. Because it reads all the pillars, two people born in the same year can score quite differently with the same person.
Why not just compare the year animals?
Popular zodiac charts compare only the two year animals, so any two people born in, say, a Rat year and a Horse year get the same answer, whoever they are. The year animal is the branch of the year pillar, one of eight characters in a chart.
BaZi compatibility goes beyond the year animals. The classical texts read the day stem as the person and the day branch as the partner position (the spouse palace, 日支), so this calculator compares the two day pillars as well. It still checks the year animals, but as one signal of five, and the partner position carries the largest weight.
The pairings the calculator looks for
These are the classical relations the score counts, read from the same tables the calculator uses.
| 甲 Jia · Yang Wood | 己 Ji · Yin Earth | → Earth |
| 乙 Yi · Yin Wood | 庚 Geng · Yang Metal | → Metal |
| 丙 Bing · Yang Fire | 辛 Xin · Yin Metal | → Water |
| 丁 Ding · Yin Fire | 壬 Ren · Yang Water | → Wood |
| 戊 Wu · Yang Earth | 癸 Gui · Yin Water | → Fire |
| 子 Zi (Rat) | 丑 Chou (Ox) |
| 寅 Yin (Tiger) | 亥 Hai (Pig) |
| 卯 Mao (Rabbit) | 戌 Xu (Dog) |
| 辰 Chen (Dragon) | 酉 You (Rooster) |
| 巳 Si (Snake) | 申 Shen (Monkey) |
| 午 Wu (Horse) | 未 Wei (Goat) |
| 子 Zi (Rat) | 午 Wu (Horse) |
| 丑 Chou (Ox) | 未 Wei (Goat) |
| 寅 Yin (Tiger) | 申 Shen (Monkey) |
| 卯 Mao (Rabbit) | 酉 You (Rooster) |
| 辰 Chen (Dragon) | 戌 Xu (Dog) |
| 巳 Si (Snake) | 亥 Hai (Pig) |
| 申 Shen (Monkey) | 子 Zi (Rat) | 辰 Chen (Dragon) | Water |
| 亥 Hai (Pig) | 卯 Mao (Rabbit) | 未 Wei (Goat) | Wood |
| 寅 Yin (Tiger) | 午 Wu (Horse) | 戌 Xu (Dog) | Fire |
| 巳 Si (Snake) | 酉 You (Rooster) | 丑 Chou (Ox) | Metal |
What is free, what is paid, and what this is not
The score, every reason behind it and the share image are free, with no account. Compare as many pairs as you like.
The full report ($9, paid once) adds the written reading for each pair you compare, alongside the full reading of your own chart.
This is not a matchmaking service: there is no search for people and no profiles to browse. It compares two people who already know each other, as a way to talk about two temperaments. It is not advice on whether to start, keep or end a relationship.
Questions about BaZi compatibility
How is BaZi compatibility calculated here?
From five kinds of signal between the two charts: whether the two day masters form a classical stem pair, how the two partner positions (the day branches) relate, harmonies and clashes among the other branches, the two year animals, and whether one chart supplies an element the other lacks. Each signal has fixed points, and the total is placed on a scale of 5 to 95.
Is day master compatibility the same as zodiac compatibility?
No. Zodiac compatibility compares the two year animals, which everyone born in the same year shares. Day master compatibility looks at the stems of the two day pillars, which change every day. This calculator counts both, together with the other pillars.
Do I need the other person’s birth time?
No. Without a time, a chart has three pillars and the hour branch is simply left out of the count. If you know the time, add it with the birth city so it can be converted to local solar time.
A personality and strengths framework for self-reflection and entertainment, not a prediction of future events.