Check cron schedules across time zones and daylight saving

Start with the clock and the cron dialect

A five-field expression describes minute, hour, day of month, month and weekday. It does not include a time zone. The same 0 9 * * 1-5 can mean 09:00 UTC or 09:00 in Toronto, depending on the scheduler’s configuration. Some systems also accept seconds, a year field or extra symbols; this tool deliberately accepts the five-field UNIX form.

minute hour day-of-month month weekday

Open Cron Expression Builder, enter the expression, choose an IANA zone such as America/Toronto and provide a starting instant with Z or a UTC offset. The preview shows occurrences strictly after that instant. It does not install or execute a job.

Example 1: weekdays at 09:00 in Toronto

Expression

0 9 * * 1-5

Time zone

America/Toronto

Preview after

2026-10-19T12:00:00Z

The first result is Monday, October 19, 2026 at 09:00 in Toronto, corresponding to 2026-10-19T13:00:00.000Z. Change the zone to UTC while retaining that starting instant: the first result becomes Tuesday, October 20 at 09:00 UTC because Monday’s 09:00 UTC is already past.

Example 2: a local time that does not exist

Use 30 2 * * *, America/Toronto and 2026-03-07T12:00:00Z. Toronto’s 02:30 local time is skipped during the March 8 clock change. This preview skips that occurrence; its first result is March 9 at 02:30, or 2026-03-09T06:30:00.000Z.

Do not assume your production scheduler makes the same choice. Some schedulers shift or otherwise compensate for a missing local time. Check its documented behavior and decide whether the job should follow local wall time or a steady UTC schedule.

Example 3: a local time that happens twice

Use 30 1 * * *, America/Toronto and 2026-10-31T12:00:00Z. On November 1, 01:30 occurs twice. This preview returns the first occurrence once: 2026-11-01T05:30:00.000Z. It does not list the second 01:30 at 06:30 UTC. Its next result is November 2 at 01:30, or 2026-11-02T06:30:00.000Z.

These examples use the browser’s time-zone database and the tool’s explicit local-field checks. They are a testable description of this preview, not a guarantee about every cron service. The IANA time-zone database tracks civil-time rules; the tool’s scheduling library documents its supported cron patterns.

Before putting a schedule into production

• Verify the scheduler’s field count, day-of-month/weekday matching rule and configured time zone.
• Preview both sides of the next clock change, not just tomorrow.
• Make the job safe to retry if a duplicate run would cause harm.
• Test the actual scheduler and monitor its first runs. This browser preview searches at most eight years ahead and cannot know whether the server is running.