24 Solar Terms (절기) API
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by KunStudio · free to evaluate · no API key on origin

24 Solar Terms (절기) API

The 24 solar terms (절기) mark the sun's position around the ecliptic in 15° steps — 입춘 (Start of Spring), 하지 (Summer Solstice), 동지 (Winter Solstice) and 21 more. They drive seasonal content, farming calendars and parts of saju. This API computes their exact KST entry times for any year.

Because the terms are defined by the sun's apparent longitude, their dates and times shift year to year and can't be hard-coded. This endpoint computes them astronomically (Jean Meeus' algorithm) for any year in range, so you never ship a stale table.

The 24 solar terms (절기) around the year 24 solar terms placed at fifteen-degree steps of the sun's ecliptic longitude, forming a ring. The four cardinal terms (spring equinox 춘분, summer solstice 하지, autumn equinox 추분, winter solstice 동지) are labelled, and the four seasons are drawn as coloured arcs. The API returns each term's exact KST entry time, computed astronomically for any year. 춘분Spring Equinox하지Summer Solstice추분Autumn Equinox동지Winter Solstice 24 solar terms 절기 / jeolgi Every 15° of the sun's longitude marks one of the 24 solar terms (절기). Their dates shift year to year, so they cannot be hard-coded. This API computes each term's exact KST entry time astronomically (Meeus) for any year. Spring · 봄 Summer · 여름 Autumn · 가을 Winter · 겨울
The 24 solar terms (절기) around the year — one every 15° of the sun's ecliptic longitude. The four cardinal terms (equinoxes and solstices) are labelled; the API returns each term's exact KST entry time for any year.

Endpoints

GET /v1/solar-terms?year=2026 All 24 solar terms for a year with KST entry times (Hangul, romanized, English, sun longitude).
GET /v1/solar-terms?date=2026-03-20 Check whether a specific KST date is one of the 24 solar terms (returns the term or null).

Example request & response

curl "https://korea-calendar-api.kunstudio.workers.dev/v1/solar-terms?year=2026"
{
  "year": 2026,
  "count": 24,
  "solar_terms": [
    {
      "date": "2026-02-04",
      "time_kst": "04:54",
      "datetime_kst": "2026-02-04T04:54:41+09:00",
      "name": "입춘",
      "romanized": "Ipchun",
      "name_en": "Start of Spring",
      "sun_longitude": 315
    }
    // ... 23 more
  ]
}

No API key is needed on the origin to try this — it is rate-limited for fair evaluation. See the OpenAPI spec for the full schema.

Good to know

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