ISO Week Calendar Converter: practical workflow and limits

Resolve an ISO week into Monday–Sunday dates and convert a date back to its week.

Use the guide alongside the working tool.

Try the local sample

{
  "start": "2026-11-01",
  "end": "2026-12-31",
  "zone": "UTC",
  "weekends": "0,6",
  "holidays": "",
  "year": "2026",
  "week": "45",
  "date": "2026-11-05"
}

Resolve an ISO week into Monday–Sunday dates and convert a date back to its week. ISO weeks start Monday; week 1 contains January 4. ISO week-year can differ from the calendar year. Invalid week 53 is rejected. This does not change the locale’s preferred week numbering.

Prepare the calendar

Resolve an ISO week into Monday–Sunday dates and convert a date back to its week.

Use the sample to inspect the exact workflow. Set the planning range and replace the demonstration entries with your own dates.

Check the assumptions

ISO weeks start Monday; week 1 contains January 4. ISO week-year can differ from the calendar year. Invalid week 53 is rejected. This does not change the locale’s preferred week numbering.

Dates are inclusive in planning inputs unless labeled exclusive. Timed events require a valid IANA timezone; ambiguous daylight-saving times are rejected.

Keep and share the result

Review warnings and totals, then export the supported ICS, CSV, JSON or report formats. Exports contain the chosen data, so review sensitive names and notes before sharing.

No calendar account is connected and no reminder is scheduled by this website. Import the ICS file explicitly into a calendar app; save a JSON draft if you want to continue editing later.

Ready to apply this workflow?

Try ISO Week Calendar Converter →

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All practical guides →

Keep your original files and review the result. Found unclear instructions? Contact Team Hypomnema.