---
title: "Year Pillar"
method: POST
path: "/bazi/year-pillar"
tags: ["BaZi (Four Pillars)"]
---

# Year Pillar

`POST /bazi/year-pillar`

Year stem + branch + animal + element with yin/yang.

## Request body

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

## Response `200`

Successful calculation

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

## Other responses

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

## Changes

- **2026-08-22** `5a17388652f3` — 1 breaking, 2 info
  - added the new required request property `date`
  - added the new optional request property `time`
  - added the new optional request property `timezoneOffset`

[Change history](https://skmtc.dev/astroway/apis/astroway-calculation-api/changes/bazi/year-pillar/post.md)

---

[API](https://skmtc.dev/astroway/apis/astroway-calculation-api.md) · [All operations](https://skmtc.dev/astroway/apis/astroway-calculation-api/llms.txt) · [OpenAPI document](https://skmtc-service-production.skmtc.workers.dev/v1/apis/astroway/astroway-calculation-api/revisions/4ed0fa90d9dc/schema)