---
title: "Four Pillars (full)"
method: POST
path: "/bazi/four-pillars"
tags: ["BaZi (Four Pillars)"]
---

# Four Pillars (full)

`POST /bazi/four-pillars`

All four pillars: year, month, day, hour. Day pillar uses the canonical 60-jiazi cycle (anchor 1990-01-01 = Bing-Yin). Pass `time` to compute the hour pillar; day and hour roll at 23:00 local, year and month at the exact Lichun and 節 instants.

## Request body

- BaziFourPillarsInput
  - `date` string, required
  - `time` string
  - `timezoneOffset` number

## Response `200`

Successful calculation

- object
  - `ok` boolean
  - `data` object
    - `yearPillar` object, nullable
      - `pillar` string, nullable
    - `monthPillar` object, nullable
      - `pillar` string, nullable
    - `dayPillar` object, nullable
      - `pillar` string, nullable
      - `stem` string, nullable
      - `branch` string, nullable
      - `animal` string, nullable
      - `stemElement` string, nullable
      - `branchElement` string, nullable
      - `yin` boolean, nullable
    - `hourPillar` object, nullable
      - `pillar` string, nullable

## Other responses

- `400` — Validation error
- `401` — Missing or invalid API key

---

[API](https://skmtc.net/astroway/apis/astroway-calculation-api.md) · [All operations](https://skmtc.net/astroway/apis/astroway-calculation-api/llms.txt) · [OpenAPI document](https://skmtc-service-staging.skmtc.workers.dev/v1/apis/astroway/astroway-calculation-api/revisions/529d7d36d7d6/schema)