*/5 for every 5 units, 1-5 for ranges, and commas for lists.How it works
The Crontab Generator builds valid cron expressions from a human-readable schedule configuration and translates existing cron expressions back into plain English. It eliminates the need to memorize cron's cryptic five-field syntax.
Cron is the standard Unix/Linux job scheduler. A cron expression defines when a job runs: every minute, daily at 3am, every weekday at noon, the first of every month. The five-field syntax (minute hour day-of-month month day-of-week) is powerful but non-obvious — a single misplaced asterisk can turn a daily job into one that runs every minute.
How to use it: use the visual schedule builder (pick frequency, time, day, month) to generate the cron expression, or paste an existing expression and click "Explain" to get plain English. The preview shows the next 10 scheduled run times so you can confirm the expression does what you expect.
Expression fields explained: - Field 1 (Minute): 0–59. An asterisk (*) means "every minute." - Field 2 (Hour): 0–23. 0 = midnight, 12 = noon. - Field 3 (Day of month): 1–31. - Field 4 (Month): 1–12 or JAN–DEC. - Field 5 (Day of week): 0–7 (both 0 and 7 = Sunday) or SUN–SAT.
Special syntax: */5 means "every 5 units," 1-5 means "1 through 5," 1,3,5 means "1, 3, and 5." The @ shortcuts (@hourly, @daily, @weekly, @monthly, @reboot) are also supported and explained.
Platform notes: standard cron and AWS CloudWatch Events both use 5-field expressions. Kubernetes CronJobs, GitHub Actions schedules, and Quartz Scheduler use variations — the tool shows the exact syntax for each platform.
Frequently Asked Questions
- Use */5 in the minutes field: '*/5 * * * *'. The */ syntax means 'every N units'. For every 15 minutes: '*/15 * * * *'. For every hour: '0 * * * *' (runs at minute 0 of every hour).
- In standard cron, both 0 and 7 represent Sunday in the day-of-week field. This is a historical quirk — use 0 for maximum compatibility with all cron implementations.
- Standard Unix cron (5 fields) does not support seconds — the minimum interval is one minute. Quartz Scheduler (used in Java applications) uses a 6-field format with seconds. AWS CloudWatch Events and Kubernetes CronJobs use the standard 5-field format.
- '30 2 * * 1-5' — minute 30, hour 2, any day of month, any month, Monday through Friday (1–5). The tool's next-run preview confirms the schedule is correct.