Cron expression explainer
Read a five-field cron schedule in plain terms and list its next run times.
A clear answer. Here’s how.
Parses the five standard cron fields into the exact values each allows, then walks forward day by day to list every matching minute after the start time. Weekday 7 means Sunday. As in Vixie cron, a day matches when either day-of-month or weekday matches if both fields are restricted, and when both match if either starts with an asterisk. Times are UTC; seconds fields and Quartz extensions (L, W, #, ?) are not supported. Searches up to eight years ahead.
See a worked example
Worked example
A fixed demonstration, separate from the values you enter above.
- Cron expression
- */15 9-17 * * 1-5
- Start time (UTC, YYYY-MM-DD HH:MM)
- 2026-01-05 08:50
- Number of runs to list
- 10
Example result
| Run | UTC date and time | Weekday | Gap |
|---|---|---|---|
| 1 | 2026-01-05 09:00 | Monday | 10 min after the start |
| 2 | 2026-01-05 09:15 | Monday | 15 min after the previous run |
| 3 | 2026-01-05 09:30 | Monday | 15 min after the previous run |
| 4 | 2026-01-05 09:45 | Monday | 15 min after the previous run |
| 5 | 2026-01-05 10:00 | Monday | 15 min after the previous run |
Times are UTC and strictly after the start time. Uses classic Vixie-cron rules: if both day-of-month and weekday are restricted, a day matches when either matches. Your scheduler’s timezone and daylight-saving behaviour may differ.