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ISO 8601 converter

Parse and write ISO 8601 dates such as 2026-09-24T12:00:00Z. Type an ISO date or a timestamp and get it in UTC and with the offset of any time zone, plus the Unix time, the week number and the day of the year. It runs in your browser.

How to convert an ISO 8601 date

  1. 1Type or paste an ISO 8601 date, for example 2026-09-24T12:00:00Z
  2. 2Pick the time zone you want it in
  3. 3Copy the ISO string or any other format
  4. The date as ISO 8601 in UTC and in your zone.

What you get

  • Both ISO forms.UTC with a Z, and your zone with its offset like +02:00.
  • More than ISO.Unix time, HTTP date, relative time, day of year and ISO week.
  • Nothing is uploaded.The conversion runs in your browser, on your own device.

What you can do

  • Read an ISO 8601 date or date-time, with a Z or an offset, and show the same moment in any time zone.
  • Write an ISO 8601 string from a Unix timestamp in seconds, milliseconds, microseconds or nanoseconds.
  • Pick a date and time with the date picker and get its ISO 8601 string in the chosen zone.
  • Show the ISO week number (like 2026-W39) and the day of the year.
  • Show the UTC string and the zoned string, which includes the offset, next to a full date and an HTTP date.

Good to know

  • Add a Z or an offset such as +02:00 when it matters. A date-time without one is read by your browser's rules, so the result may depend on your own time zone.
  • A date without a time, like 2026-09-24, is read as midnight UTC.
  • Other date text, such as 24 Sep 2026 12:00 UTC, is read as well, and the tool shows that it was read as date text.
  • The ISO week follows ISO 8601: weeks start on Monday and week 1 holds the first Thursday of the year.

Questions

How do I convert a date to ISO 8601?

Type the date, for example 24 Sep 2026 14:30, or use the date picker. The ISO 8601 line shows it in UTC and in the zone you chose.

What does the Z at the end of an ISO date mean?

Z means UTC, zero offset. 2026-09-24T12:00:00Z is the same moment as 2026-09-24T14:00:00+02:00.

How do I get the ISO week number?

Enter the date. The result list includes the ISO week, written like 2026-W39.

Is my input uploaded?

No. Dates are parsed and converted in your browser.

Related tools

How it works

Small tools that run in your browser.

Four steps

  1. Start with a file or a task

    Drop a file, search, or pick a task.

  2. The tool opens in a window

    Open as many as you like, side by side as tabs.

  3. Results collect on the right

    Drag a result into the next tool.

  4. Save when you're done

    Saved files go to your downloads.

Who uses what

Tool sets for common jobs.

Put a tool on your home screen

The icon opens that tool, like an app.

iPhone and iPad

  1. Open the tool in Safari.
  2. Tap Share (the square with the arrow).
  3. Choose “Add to Home Screen”, then Add.

Android

  1. Open the tool in Chrome.
  2. Tap the menu (⋮) at the top right.
  3. Choose “Add to Home screen” or “Install app”.

Computer

  1. Open the tool in Chrome or Edge.
  2. Click the install icon in the address bar.
  3. Choose Install.

Skills

Claude skills we use ourselves, one job each.