ISO date quarter bounds

iso-date-quarter-bounds · version 1.0.0 · Dates & times (UTC, ISO 8601) · free, no key needed

Return the calendar quarter number and the first/last dates of the quarter containing a date.

Use when you need to: iso date quarter bounds · calendar quarter of a date · quarter start and end dates.

Supported

• iso date quarter bounds
• calendar quarter of a date
• quarter start and end dates

Not supported

• fiscal quarters
• timezones
• datetime input

Behavior

• date is a proleptic Gregorian UTC calendar date YYYY-MM-DD with years 0001-9999.
• quarter is 1 for months 1-3, 2 for months 4-6, 3 for months 7-9, 4 for months 10-12 of the calendar year of date.
• start is the first day of the quarter and end is the last day of the quarter, both YYYY-MM-DD.
• No fiscal-year offset is applied; quarters follow the calendar year.

Input

• date (string, required): min length 10; max length 10; pattern ^\d{4}-\d{2}-\d{2}$

Output

• quarter (integer, required): min 1; max 4
• start (string, required): min length 10; max length 10
• end (string, required): min length 10; max length 10

Limits

• year min: 1
• year max: 9999

Example

Request input:

{
  "date": "2026-02-10"
}

Response:

{
  "result": {
    "quarter": 1,
    "start": "2026-01-01",
    "end": "2026-03-31"
  }
}

How to call it

MCP

Connect https://computefirst.net/mcp (setup), then call execute with:

{
  "id": "iso-date-quarter-bounds",
  "version": "1.0.0",
  "input": {
    "date": "2026-02-10"
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/iso-date-quarter-bounds/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"date":"2026-02-10"}'

The machine-readable contract is at /v1/tools/iso-date-quarter-bounds/versions/1.0.0.

CLI

node cli.mjs run iso-date-quarter-bounds 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

Related tools

• ISO date week bounds: Return the Monday and Sunday of the ISO-8601 week that contains a calendar date.
• ISO date month end: Return the last valid calendar day of the year-month of a YYYY-MM-DD date.
• ISO date month start: Return the first calendar day of the year-month of a YYYY-MM-DD date.
• ISO date add years: Add a signed whole-year delta to a YYYY-MM-DD date, clamping the day if 29 February has no match.
• ISO date age: Compute the calendar-aware elapsed years, months, and days between a birth date and an as-of date.
• ISO date days in month: Return the number of calendar days in a given proleptic Gregorian year and month.