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Week Number Calculator

Calculate the week number of a date within a year. Supports different week number calculation standards (ISO 8601, US standard, etc.) for project management, time planning, and data analysis.

Process multiple dates (one per line)

Include additional date details like quarter, day of year, leap year info

Key Facts

Category
Utilities
Input Types
textarea, select, checkbox
Output Type
text
Sample Coverage
4
API Ready
Yes

Overview

The Week Number Calculator is a precise utility designed to determine the week number of any given date within a year. By supporting multiple international standards like ISO 8601 and US-based calculations, it helps professionals, project managers, and analysts align their schedules and data reporting with specific calendar requirements.

When to Use

  • •Aligning project milestones with specific calendar weeks for reporting.
  • •Converting historical dates into standardized week numbers for data analysis.
  • •Planning recurring tasks or events based on specific week-start conventions.

How It Works

  • •Enter your target date or a list of dates into the input field.
  • •Select your preferred week standard (e.g., ISO 8601, US, or European) to define how weeks are counted.
  • •Optionally adjust advanced settings like the start day of the week or first-week criteria.
  • •Generate the results in your chosen format, such as a simple list, table, or JSON.

Use Cases

Project management scheduling and sprint planning.
Financial reporting and quarterly performance tracking.
Standardizing date-based data for database imports.

Examples

1. Project Sprint Planning

Project Manager
Background
A project manager needs to map out 12 weeks of development sprints starting from a specific launch date.
Problem
Manually identifying the correct week numbers for each sprint date is prone to error.
How to Use
Input the start dates of each sprint, select 'ISO 8601' as the standard, and choose 'Table' as the output format.
Example Config
weekStandard: iso, outputFormat: table, includeDateInfo: true
Outcome
A clean table showing the date, corresponding ISO week number, and quarter for each sprint.

2. Annual Sales Reporting

Data Analyst
Background
An analyst is preparing a yearly sales report that requires grouping daily transaction data into weekly buckets.
Problem
The raw data lacks week numbers, making it difficult to aggregate sales by week.
How to Use
Paste the list of transaction dates, select 'US Standard', and choose 'CSV' to easily import the results back into a spreadsheet.
Example Config
weekStandard: us, outputFormat: csv, multipleDates: true
Outcome
A CSV file containing the original dates paired with their US-standard week numbers, ready for pivot table analysis.

Try with Samples

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EU VAT Number Samples
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Passport Number Samples
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FAQ

What is the difference between ISO 8601 and US standards?

ISO 8601 starts weeks on Monday and defines the first week of the year as the one containing the first Thursday. The US standard typically starts on Sunday and considers the week containing January 1st as the first week.

Can I calculate week numbers for multiple dates at once?

Yes, simply enable the 'Multiple Dates' option and enter one date per line in the input box.

Does this tool support leap years?

Yes, the calculator automatically accounts for leap years when determining the week number and day of the year.

What output formats are available?

You can export your results as a simple list, a formatted table, a JSON array, or CSV format.

Can I customize the start day of the week?

Yes, you can override the standard settings by selecting a specific start day like Monday, Sunday, or Saturday in the advanced settings.

API Documentation

Request Endpoint

POST /en/api/tools/week-number-calculator

Request Parameters

Parameter Name Type Required Description
dateInput textarea Yes -
weekStandard select Yes -
multipleDates checkbox No Process multiple dates (one per line)
outputFormat select Yes -
includeDateInfo checkbox No Include additional date details like quarter, day of year, leap year info
startOfWeek select No -
firstWeekContains select No -

Response Format

{
  "result": "Processed text content",
  "error": "Error message (optional)",
  "message": "Notification message (optional)",
  "metadata": {
    "key": "value"
  }
}
Text: Text

AI MCP Documentation

Add this tool to your MCP server configuration: 

{
  "mcpServers": {
    "elysiatools-week-number-calculator": {
      "name": "week-number-calculator",
      "description": "Calculate the week number of a date within a year. Supports different week number calculation standards (ISO 8601, US standard, etc.) for project management, time planning, and data analysis.",
      "baseUrl": "https://elysiatools.com/mcp/sse?toolId=week-number-calculator",
      "command": "",
      "args": [],
      "env": {},
      "isActive": true,
      "type": "sse"
    }
  }
}

You can chain multiple tools, e.g.: `https://elysiatools.com/mcp/sse?toolId=png-to-webp,jpg-to-webp,gif-to-webp`, max 20 tools.

If you encounter any issues, please contact us at [email protected]