ISO 8601 is the international standard for representing dates and times, such as 2026-05-29T12:00:00.000Z. It avoids ambiguity by ordering fields from largest to smallest.

What is the basic format?

The basic format removes the separators, giving a compact string like 20260529T120000Z, which is sometimes required by file names or older systems.

Is anything uploaded?

No. The formatter uses the browser's native Date and Intl APIs locally, so your dates never leave the page.

ISO 8601 Date Formatter

Format any date as a standards-compliant ISO 8601 string.

ISO 8601 date formatter

Type any date — an ISO string, a casual format, or just “use now” — and get back a clean, standards-compliant ISO 8601 representation in several variants: full UTC, local time with offset, date-only, the compact basic format, and the ISO week date (year-Wweek-day).

Each output is one click to copy. Everything runs in your browser using native Date and Intl APIs, so nothing is uploaded.