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ISO 8601 Parser & Generator
Parse an ISO 8601 value and inspect its UTC instant, Unix timestamps, source offset, local representation, and calendar details.
Normalized formats
2026-09-01T08:30:00Z
2026-09-01T08:30:00.000Z
Unix timestamps
1788251400
1788251400000
Z
Calendar details
Tuesday
244
2026-W36
No
None
UTC (Z)
✓ Parsed and generated locally in your browser
Parse ISO 8601 without browser guesswork
The parser validates calendar dates, times, fractional seconds, and offsets explicitly. Values with Z or an offset are converted to UTC deterministically. A date without a time is treated as a UTC calendar date, while a date-time without an offset is clearly identified as browser-local time.
Generate portable timestamps
Choose a date, time, UTC offset, and fractional-second precision to generate a normalized timestamp for APIs, logs, databases, and test data. Use Z for UTC or include a numeric offset when the source wall-clock time matters.
Frequently asked questions
What is ISO 8601?
ISO 8601 is an international date and time representation standard. A common internet form is 2026-09-01T08:30:00Z, where T separates the date and time and Z means UTC.
What is the difference between Z and a numeric offset?
Z represents UTC with zero offset. Values such as +08:00 and -04:00 describe local clock time at a fixed offset from UTC. Different representations can refer to the same instant.
What happens when an ISO date-time has no offset?
This tool interprets a date-time without Z or a numeric offset in the browser’s local time zone and displays a warning. Include an offset when the instant must be unambiguous.
Is the date sent to a server?
No. Parsing and conversion happen locally in your browser.