Four Pillars Calculator

Your Bazi Chart

Enter your birth details to calculate your Four Pillars using documented Zi Ping conventions. Results are generated entirely in your browser.

Birth Details

Birth Date

Birth Time (local clock time, 24-hour)

Gender (used for some interpretations)

Time Zone (UTC offset)

True Solar Time correction (optional)

Adjusts clock time for your longitude difference from the UTC meridian. Note: equation of time is not applied (known limitation).

Zi Hour (子時) convention used on this site: The Zi hour spans 23:00 to 01:00 across midnight. We use the Early Zi convention: births at 23:00 to 23:59 belong to the current calendar day (the day stem before midnight). Births at 00:00 to 00:59 belong to the new calendar day. If your practitioner uses a different convention, adjust accordingly.

The Four Pillars

Day Master (日主)

Your Day Master is the anchor of the chart - the reference point from which all other stems and branches are interpreted.

Five Elements Balance (五行)

Distribution of Wood, Fire, Earth, Metal, and Water across your four pillars and hidden stems.

Day Master Strength (旺衰) and Favourable Elements

Strength is assessed using a simplified rule-based heuristic: seasonal support (月令), rootedness in branches, and stem support. This is a transparent heuristic, not a master's bespoke analysis.

Ten Gods (十神) Mapping

The relationship between your Day Master and each other stem in the chart reveals the Ten Gods - the archetypes that colour different areas of life.

Favourable Associations

Colours, directions, seasons, and materials traditionally linked to your favourable elements.

Feng Shui Directions

Your Bazi reveals your favourable elements and colours. The Eight Mansions system maps those to compass directions. Calculate your Kua number to find your personal favourable and unfavourable directions.

Find My Kua Directions

Save My Chart

Save your chart to this browser. Your data stays on your device and is used to power future daily readings. Nothing is sent to any server.

About Our Method

◆System: Zi Ping (子平) Four Pillars, the mainstream classical method used by most Bazi practitioners.
◆Year boundary: The astrological year begins at Li Chun (立春, roughly February 4), when the sun enters 315 degrees ecliptic longitude. Not January 1 and not the Lunar New Year.
◆Month boundary: Each of the 12 Chinese solar months begins at a Jie (節) solar term. We use a lookup table of accurate solar term dates for 1920 to 2030 (cross-referenced against USNO/Jean Meeus astronomical data).
◆Day pillar anchor: 1900-01-31 (Gregorian) is Jia Zi (甲子), cycle index 0. All day pillars are counted from this documented anchor.
◆Hour stem rule: Five Rats (五鼠遁) - the hour stem is derived from the day stem and the hour branch.
◆Month stem rule: Five Tigers (五虎遁) - the month stem is derived from the year stem and the solar month number.
◆Zi hour convention: Early Zi - births at 23:00 to 23:59 use the current day's stem; births at 00:00 to 00:59 use the next day's stem.
◆Day Master strength: Assessed by a simplified heuristic considering seasonal support (monthly branch), rootedness in branches, and stem support. Stated as simplified on every reading.
◆What this is not: A master's personalised reading. The interpretations are transparent, rule-based outputs. For deep analysis, consult a qualified Bazi practitioner. For Chinese zodiac, we link to birthchartnumbers.com.

For cultural interest and self-reflection only. Not fate, medical, or financial advice.

Frequently Asked Questions

Does the Bazi Year Start at Chinese New Year or Li Chun?

The astrological year begins at Li Chun, roughly February 4, when the sun reaches 315 degrees ecliptic longitude. It does not begin on January 1 and it does not begin at Lunar New Year. Anyone born in January or early February therefore belongs to the previous solar year for the Year Pillar. This is the single most common source of error in automated Bazi charts.

How Are the Month Boundaries Calculated?

Each of the twelve Chinese solar months begins at a Jie solar term, not on a fixed calendar date. This calculator uses a lookup table of accurate solar term dates for 1920 to 2030, cross referenced against USNO and Jean Meeus astronomical data, so the month pillar changes on the correct day rather than an approximate one.

How Is the Day Pillar Anchored?

All day pillars are counted from a documented anchor: 31 January 1900 in the Gregorian calendar is Jia Zi, cycle index 0. Because the sexagenary day cycle runs unbroken, every later day pillar follows by simple counting from that anchor.

Which Convention Is Used for the Zi Hour?

This calculator uses the Early Zi convention. Births between 23:00 and 23:59 use the current day's stem, while births between 00:00 and 00:59 use the next day's stem. The hour stem itself comes from the Five Rats rule, derived from the day stem and the hour branch.

What Can This Calculator Not Tell You?

It cannot give you a master's personalised reading. The interpretations are transparent, rule based outputs, and Day Master strength in particular is assessed by a simplified heuristic that is labelled as simplified on every reading. For deeper analysis, consult a qualified Bazi practitioner. This is offered for cultural interest and self reflection only, and it is not fate, medical, or financial advice.