Cron Explainer

Explain a five-field Cron expression and inspect the next five occurrences in an explicit timezone.

Five fields: minute hour day-of-month month weekday. Supports *, lists, ranges, steps, JAN–DEC and SUN–SAT. No seconds, commands or Quartz extensions.

ISO 8601 with Z or an explicit offset, for example 2026-09-16T00:00:00Z. The reference instant itself is excluded. Years 0001–9994.

Choose a suggestion or enter an IANA name, such as Asia/Seoul. The reference instant stays absolute when the zone changes.

This tool explains dates locally. It does not run commands, create jobs or send your expression and dates to a server.

Report a problem

Next occurrences

Explain a schedule to see its constraints and next occurrences.

Calendar rules and limits

If day-of-month and weekday are both different from literal *, either may match (OR). If one is *, the other controls the day. Ranges and steps, including */1, count as restrictions. Month, hour and minute must always match.

Nonexistent local times during a clock jump are skipped. On a repeated hour, schedules with restricted hours traverse that hour once; schedules allowing all 24 hours can show both offsets. Results show an explicit UTC offset and UTC instant.

Shows up to five occurrences within 1,830 days after the reference. Expressions are limited to 256 characters. Calculation runs in a worker with a 2-second budget. Timezone rules come from your browser.

About Cron Explainer

Explain a five-field Cron schedule and preview its next five occurrences.

Provide minute, hour, day of month, month and weekday, an IANA timezone and an ISO reference time with Z or an offset.

Use local time, UTC offset and UTC instant together to check a scheduler setting; this page does not create jobs.

The calculation or rendering runs in this browser tab. Copy, download and share actions make the chosen output available outside this tab.

Worked example

Input / settings
*/15 * * * *; UTC; 2026-09-16T12:00:00Z
Action
Calculate next occurrences
Result
12:15, 12:30, 12:45, 13:00 and 13:15 UTC on 2026-09-16.

Scope and limits

  • Searches up to 1,830 days with a 2,000ms worker budget. No seconds, macros or Quartz ? L W # syntax. Day-of-month and weekday use OR when both are restricted.

Frequently asked questions

How are daylight-saving changes handled?
Missing local times are skipped. Restricted-hour schedules visit a repeated hour once; schedules spanning all hours can include both offsets. Review the UTC values for your scheduler.

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