Cron expression generator
Build a 5-field cron expression, explain each field, and preview the next local runs.
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Tool guide
Cron expression generator: how it works
Practical information to understand the result and use this tool correctly.
About Cron expression generator
A standard crontab line has five fields: minute, hour, day of month, month, and day of week.
The generator previews the next five matches in your local timezone without uploading the schedule.
How to use it
- 1Enter five fields or load a preset. Empty, negative, and NaN tokens are rejected; 0 is valid for minute, hour, and Sunday.
- 2Load every 15 minutes, weekdays at 08:30, or hourly.
- 3Read the field summary and the next local runs. If both day fields are set, matching uses OR.
- 4Copy the expression or reset. Nothing is uploaded.
Frequently asked questions
- What does */15 * * * * run next after 12:07?
- Every 15 minutes: 12:15, 12:30, 12:45, 13:00, and 13:15 local. The step starts at minute 0, so 0, 15, 30, and 45.
- What does 30 8 * * 1-5 mean on a Tuesday after 09:00?
- Weekdays at 08:30. The next run is Wednesday 08:30, then Thursday, Friday, and the following Monday. Saturday and Sunday are skipped.
- Which formula and units are used?
- Fields are minute 0–59, hour 0–23, day of month 1–31, month 1–12, weekday 0–7 (0 and 7 are Sunday). There is no SI unit. If both day fields are restricted, Vixie crontab uses OR.
- What happens with empty, zero, negative, or NaN?
- Any empty field is an error. Minute 0 and hour 0 are valid. A leading minus, NaN, or a step of 0 is invalid. Six-field cron with seconds is not accepted.