Saju Compatibility: Four Pillars Match for Two People

Traditional factors and branch tables

The public-domain classical text San Ming Tong Hui (https://zh.wikisource.org/wiki/三命通會) describes traditional stems, branches and their combinations. The five stem pairs used here are Jia–Ji, Yi–Geng, Bing–Xin, Ding–Ren and Wu–Gui; a pairing does not imply an element transformation.

The Earthly Branches overview (https://en.wikipedia.org/wiki/Earthly_Branches) provides background on the symbolic system. This page uses four trine groups, six harmony pairs, six clashes, six harms, punishment groups and six breaks. Two members of a three-branch group are marked as a partial pair; identical Dragon, Horse, Rooster and Pig branches use the self-punishment rule. All simultaneous relations remain visible.

Korean Wonjin is presented as a traditional caution pair, separately on day and year branches. The table is Rat–Goat, Ox–Horse, Tiger–Rooster, Rabbit–Monkey, Dragon–Pig and Snake–Dog. These classifications do not establish relationship outcomes.

Calendar and clock conventions

The Hong Kong Observatory's solar-term explanation (https://www.hko.gov.hk/en/gts/time/24solarterms.htm) describes the seasonal divisions. Here the year changes at the exact Start of Spring instant and months at the twelve jie terms; year animals therefore follow the Four Pillars solar-year convention, which differs from the Lunar New Year convention on the animal-only page.

Midnight is the default day boundary. Late Zi hour from 23:00 keeps the current day pillar and uses the following day's hour stem; the optional 23:00 boundary advances both. Without a time, local noon is used and the hour pillar is omitted. Dates from 1901 to 2099 are supported.

NOAA's General Solar Position Calculations (https://gml.noaa.gov/grad/solcalc/solareqns.PDF) supplies the approximate equation of time. Optional true solar time adjusts the day and hour clock for longitude and that approximation, while solar-term comparisons use the actual instant. A named zone uses its historical offset, and a manual offset can override it.

Element counting and the transparent tally

Each visible stem and each branch's main element counts once. Hidden stems and seasonal weights are excluded; this counts symbols rather than assessing element strength. Missing birth times give six counts, and known times give eight.

Every tied weakest element is checked against the other chart's tied strongest elements. A complement counts only if the other chart also has a strictly larger proportion of that element, so six- and eight-symbol charts remain comparable. Each directional complement counts once as a neutral observation of the traditional element-balancing idea.

Five stem combinations, generating day masters, six harmonies, partial trines and element complements count as harmonising factors. Overcoming day masters, clashes, harms, punishments, breaks and Wonjin count as tension factors. Day and year scopes are separate, every overlapping rule counts and no weights or percentages are assigned.

How to use it

1. Enter two birth dates and optional times, with a city or time zone if needed.
2. Compare the day masters, spouse palaces, year animals, Wonjin pairs and five-element counts.
3. Inspect the counted factors or create a partial-chart invitation and a share card.

Privacy & limitations

Birth calculations run in your browser. Invite links contain only one day stem and branch, one year branch and five element counts, plus a first name only when selected. The share card contains no birth details or pillars.