How to Read and Build Cron Expressions
Understand the five cron fields and build reliable schedules for scripts, backups, and recurring jobs.
Using the free tool while you read? Open Cron Explainer.
The five fields
A standard cron expression contains five space-separated fields: minute, hour, day of month, month, and day of week. The command itself comes after those fields in a crontab.
- Minute: 0–59
- Hour: 0–23
- Day of month: 1–31
- Month: 1–12
- Day of week: 0–6, where 0 is Sunday
Common operators
An asterisk means every allowed value. A comma creates a list, a hyphen creates a range, and a slash sets an interval. For example, */15 in the minute field means every 15 minutes.
Useful examples
0 9 * * 1-5 runs at 9:00 AM from Monday through Friday. 0 0 1 * * runs at midnight on the first day of each month. Always confirm the server timezone before relying on a schedule.
Build before you deploy
Use the Cron Builder to select each field, inspect the plain-English explanation, and copy the final expression. Test important jobs in a safe environment before enabling them in production.