Cron Expression Explainer

How cron expressions work

A standard cron expression has five fields separated by spaces. Each field restricts when the job may run; the job fires every minute that matches all of them.

┌───────────── minute        (0–59)
│ ┌─────────── hour          (0–23)
│ │ ┌───────── day of month  (1–31)
│ │ │ ┌─────── month         (1–12 or JAN–DEC)
│ │ │ │ ┌───── day of week   (0–7 or SUN–SAT; 0 and 7 are Sunday)
│ │ │ │ │
* * * * *

Special characters

• *: any value (“every minute”, “every hour”, …).
• */n: every nth value, e.g. */15 in the minute field is every 15 minutes.
• a-b: an inclusive range, e.g. 1-5 is Monday through Friday in the day-of-week field.
• a,b,c: a list, e.g. 0,30 runs on the hour and half hour.
• a-b/n: every nth value within a range.
• Macros: @hourly, @daily, @weekly, @monthly, @yearly.

The day-of-month / day-of-week gotcha

If both the day-of-month and day-of-week fields are restricted (neither starts with *), cron runs when either matches, not both. So 0 0 13 * 5 runs at midnight on every 13th and every Friday, not only on Friday the 13th.

Common examples

• 0 * * * *: at the start of every hour.
• 30 2 * * *: every day at 02:30.
• 0 9 * * 1-5: weekdays at 09:00.
• 0 0 1 * *: midnight on the first of every month.

Cron runs in the server's time zone (often UTC). The run times above are shown in your browser's local time zone. If a scheduled job posts to a webhook, you can debug the payload with the Webhook Payload Inspector.