{
  "id": "days-until-st-patricks-day",
  "version": "d8e7fb136f15",
  "status": "published",
  "name": "Days Until St. Patrick’s Day",
  "question": "Days until St. Patrick’s Day",
  "summary": "Counts the days from today, or any date you choose, to the next St. Patrick’s Day, with its date and day of the week.",
  "category": "days",
  "subcategory": "countdowns",
  "url": "https://www.acalculator.org/days/days-until-st-patricks-day",
  "markdown": "https://www.acalculator.org/days/days-until-st-patricks-day.md",
  "kind": "function",
  "method": "Find the first date of St. Patrick’s Day on or after the start date, then count the days from the start date to it.",
  "assumptions": [
    "St. Patrick’s Day is March 17 every year.",
    "Start dates from January 1, 1900 to December 31, 2400 work, because the date field accepts that range.",
    "The start date itself is not counted: from the day before, the count is 1; on the day itself, it is 0.",
    "Dates are calendar days with no time of day, so a time zone or a daylight-saving change never adds or loses a day."
  ],
  "inputs": {
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "object",
    "properties": {
      "from": {
        "title": "Count from",
        "description": "The date to count from. Today, unless you change it.",
        "type": "string",
        "format": "date"
      }
    }
  },
  "outputs": {
    "days": {
      "label": "Days until St. Patrick’s Day",
      "description": "Whole days from the start date to the next St. Patrick’s Day; 0 on the day itself.",
      "format": "integer"
    },
    "date": {
      "label": "Date",
      "description": "The next date of St. Patrick’s Day on or after the start date.",
      "format": "date-long"
    },
    "weekday": {
      "label": "Day of the week",
      "description": "The weekday of that date.",
      "format": "text"
    },
    "weeks": {
      "label": "In weeks",
      "description": "The same number of days in weeks and days.",
      "format": "text"
    }
  },
  "defaultAnswer": {
    "inputs": {
      "from": "2026-09-29"
    },
    "outputs": {
      "days": 169,
      "date": "2027-03-17",
      "weekday": "Wednesday",
      "weeks": "24 weeks and 1 day"
    },
    "text": "From September 29, 2026, there are 169 days until St. Patrick’s Day on Wednesday, March 17, 2027."
  },
  "examples": [
    {
      "given": {
        "from": "2026-01-01"
      },
      "expect": {
        "date": "2026-03-17",
        "days": 75
      },
      "source": "the rule written again in Python 3 (datetime); docs/progress/WP-43.md"
    },
    {
      "given": {
        "from": "2026-03-18"
      },
      "expect": {
        "date": "2027-03-17",
        "days": 364
      },
      "source": "the rule written again in Python 3 (datetime); docs/progress/WP-43.md"
    }
  ],
  "sources": [
    "the rule written again in Python 3 (datetime); docs/progress/WP-43.md"
  ],
  "related": [
    "days-until-spring",
    "days-until-april-fools-day",
    "days-until-easter",
    "days-until-earth-day",
    "days-until-cinco-de-mayo",
    "days-between-dates"
  ],
  "changelog": []
}