Does Start of ISO Week upload my file or text to Tool-You servers?

No. Start of ISO Week runs in this browser tab. Files stay on the device. Limit note: ISO week Monday–Sunday. Local YMD.

Should I use ISO Week Number instead of Start of ISO Week?

Use Start of ISO Week when you need Monday and Sunday of that ISO week. Use ISO Week Number when you need ISO-8601 week and ISO year. They share a category (Date & time) but not the same job.

Start of ISO Week

Monday and Sunday of that ISO week.

Returns the Monday start and Sunday end of the ISO-8601 week that contains the date. Unlike ISO Week Number this is a date range, not week and year numbers. Local dates only.

What Start of ISO Week does

Returns the Monday start and Sunday end of the ISO-8601 week that contains the date. Unlike ISO Week Number this is a date range, not week and year numbers. Local dates only.

The interactive controls for Start of ISO Week load after this article so crawlers still read the instructions. Path /datetime/start-of-iso-week is the canonical address. Work happens on this device; Tool-You does not take a copy of the file or pasted text for Start of ISO Week.

How to use Start of ISO Week

Confirm you need Start of ISO Week, not ISO Week Number (ISO-8601 week and ISO year.). Address: /datetime/start-of-iso-week.
Enter the numbers or dates Start of ISO Week uses. Monday and Sunday of that ISO week.
Read the result as Start of ISO Week defines it — not as Weekday Name (Weekday name, ISO 1–7, and Sunday-based 0–6.). Returns the Monday start and Sunday end of the ISO-8601 week that contains the date. Unlike ISO Week Number this is a date range, not week and year numbers. Local dates only.
Start of ISO Week is an estimate in the browser, not professional advice. ISO week Monday–Sunday. Local YMD.
Need a different formula? Try Weekday Name (Weekday name, ISO 1–7, and Sunday-based 0–6.) instead of stretching Start of ISO Week.

When not to use Start of ISO Week

Skip Start of ISO Week when a neighbor tool matches better — start with ISO Week Number or Weekday Name — or when the description already warns the job will fail. In the tool’s own words: Returns the Monday start and Sunday end of the ISO-8601 week that contains the date. Unlike ISO Week Number this is a date range, not week and year numbers. Local dates only.

Questions about Start of ISO Week

What does Start of ISO Week do that other Date & time pages on this site do not?: Returns the Monday start and Sunday end of the ISO-8601 week that contains the date. Unlike ISO Week Number this is a date range, not week and year numbers. Local dates only. Short version: Monday and Sunday of that ISO week.
Does Start of ISO Week upload my file or text to Tool-You servers?: No. Start of ISO Week runs in this browser tab. Files stay on the device. Limit note: ISO week Monday–Sunday. Local YMD.
Should I use ISO Week Number instead of Start of ISO Week?: Use Start of ISO Week when you need Monday and Sunday of that ISO week. Use ISO Week Number when you need ISO-8601 week and ISO year. They share a category (Date & time) but not the same job.
What are the limits of Start of ISO Week?: ISO week Monday–Sunday. Local YMD. Also: Returns the Monday start and Sunday end of the ISO-8601 week that contains the date. Unlike ISO Week Number this is a date range, not week and year numbers. Local dates only.