---
title: "Week Number Calculator"
method: GET
path: "/api/calc/week-number-calculator"
tags: ["DateTime"]
---

# Week Number Calculator

`GET /api/calc/week-number-calculator`

## Request

- Base URL: `https://calcbright.com`
- URL: `https://calcbright.com/api/calc/week-number-calculator`
- Auth: none declared

January 1, 2026 is in ISO week 1, which began on December 29, 2025. Get the week number of any date, its Monday and Sunday, the day of the year and days left.

## Query parameters

- `date` string, date: Date Leave empty to use today's date. (YYYY-MM-DD)

## Response `200`

Calculation result

- CalcOutput
  - `ok` boolean
  - `tool` string
  - `name` string
  - `url` string: Open this link to see the full calculation
  - `inputs` object
  - `summary` string: Plain-text answer
  - `details` string
  - `result` object
  - `errors` object

## Other responses

- `400`: Invalid input (see errors)

---

[API](https://skmtc.dev/calcbright/apis/calcbright-calculator-api.md) · [All operations](https://skmtc.dev/calcbright/apis/calcbright-calculator-api/llms.txt) · [OpenAPI document](https://skmtc.dev/calcbright/apis/calcbright-calculator-api/revisions/f58229e56e58?raw)