# 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:

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

Response:

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

## How to call it

### MCP

Connect `https://computefirst.net/mcp` ([setup](/docs#connect)), then call `execute` with:

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

### HTTP (no key)

```sh
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](/v1/tools/iso-date-quarter-bounds/versions/1.0.0).

### CLI

```sh
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/](/clients/cli/).

## Related tools

- [ISO date week bounds](/tools/iso-date-week-bounds): Return the Monday and Sunday of the ISO-8601 week that contains a calendar date.
- [ISO date month end](/tools/iso-date-month-end): Return the last valid calendar day of the year-month of a YYYY-MM-DD date.
- [ISO date month start](/tools/iso-date-month-start): Return the first calendar day of the year-month of a YYYY-MM-DD date.
- [ISO date add years](/tools/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](/tools/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](/tools/iso-date-days-in-month): Return the number of calendar days in a given proleptic Gregorian year and month.