How do I run a job every 5 minutes?

Use */5 * * * *. In Quartz, 0 */5 * * * ?. In GitHub Actions, 5 minutes is the shortest interval allowed.

Why does my cron with day of month and day of week run more often than expected?

When both fields are set, cron runs if either one matches. 0 0 13 * 5 runs on every 13th and every Friday. To run only on Friday the 13th, schedule 0 0 * * 5 and check the date in the command, for example with [ "$(date +\%d)" = 13 ] && ... (in crontab, % needs a backslash).

Which time zone does cron use?

It depends on the scheduler. Crontab uses the server's time zone. GitHub Actions uses UTC by default. A Kubernetes CronJob uses the kube-controller-manager's zone unless you set spec.timeZone, for example America/New_York.

How do I schedule a job on the last day of the month?

In Quartz, use L in day of month: 0 0 23 L * ?. Standard cron has nothing like it. The usual workaround is to schedule 0 23 28-31 * * and run the command only when tomorrow is the 1st: [ "$(date -d tomorrow +\%d)" = 01 ] && ... (date -d is GNU, found in most Linux distributions).

In Linux crontab, both. Kubernetes and GitHub Actions accept 0 to 6, so 0 works everywhere. Quartz numbers days differently: Sunday is 1 and Saturday is 7. Names (SUN, MON...) avoid the confusion.

How is Quartz cron different from Linux cron?

Quartz has a seconds field at the start and an optional year at the end, counts Sunday as 1 and requires ? in one of the day fields. It also accepts L, W and #, which standard cron doesn't know. That's why 0 0 12 * * ? is Quartz and won't work in crontab.

Why did my scheduled GitHub Actions workflow run late?

GitHub warns that scheduled runs can be delayed during periods of high load, especially at the start of every hour. Scheduling at an odd minute, like 17 * * * *, usually helps. Also check that the time is in UTC.

Is the expression I type sent anywhere?

No. The explanation and the next runs are computed in your browser. The expression isn't sent to any server or to the usage metrics.

Cron Expression Generator and Explainer

Paste a cron expression to see what it does in plain English, field by field, and when it runs next in the time zone you pick. Works with crontab, Kubernetes, GitHub Actions and Quartz. You can also build the expression from the schedule you want.

Cron expression

Format

Common examples

Type or paste an expression

Or pick one of the examples. The explanation and the next runs show up here.

Build an expression

Pick how often and at what time. The expression uses the format selected above.

Frequency

Time

Days

0 9 * * 1-5At 09:00, Monday through Friday

What is a cron expression

It's a line of space-separated fields that says when a job runs. Linux crontab, Kubernetes CronJob and the GitHub Actions schedule use 5 fields. Quartz, a Java scheduler, adds seconds at the start and an optional year at the end.

The 5 fields of standard cron

The order is always minute, hour, day of month, month and day of week. 30 9 * * 1 means minute 30, hour 9, any day of the month, any month, Monday.

Field	Values
Minute	0 to 59
Hour	0 to 23
Day of month	1 to 31
Month	1 to 12 or JAN to DEC
Day of week	0 to 6 or SUN to SAT (0 is Sunday)

Asterisk, comma, hyphen and slash

* accepts any value of the field.
A comma separates values: 0,30 in minutes runs at minutes 0 and 30.
A hyphen marks a range: 1-5 in day of week is Monday to Friday.
A slash sets the step: */15 in minutes runs every 15 minutes, and 9-17/2 in hours runs at 9, 11, 13, 15 and 17.

What changes in Quartz

The first field is seconds, and Sunday is 1 (Saturday is 7). One of the day fields must be ?, meaning no value. Quartz also accepts L for the last day of the month, LW for the last weekday, 15W for the weekday nearest the 15th, 6L for the last Friday and 6#3 for the third Friday of the month.

Time zones and daylight saving time

The expression doesn't carry a time zone. Crontab uses the server's zone, GitHub Actions uses UTC and Kubernetes uses the controller's zone unless spec.timeZone is set. To run at 9:00 in New York (UTC-4 in summer) on a UTC scheduler, the hour is 13. In zones with daylight saving time, a time may not exist on the day clocks spring forward, or happen twice when they fall back. The list of runs flags both cases.

Cron expression FAQ

What people ask when scheduling jobs in crontab, Kubernetes, GitHub Actions and Quartz.