Cron Atlas

Cron expression for the 1st and 15th of the month

0 0 1,15 * *
minute0
hour0
day of month1st, 15th
monthevery month
day of weekany weekday

At 00:00, on the 1st and the 15th of the month.

Next 10 runs

In Cron, worked out in your browser from the current time.

At a glance

Runs
24 in 2027
Gap between runs
14 days to 17 days
Expressible in
All six dialects
Clock changes
No effect in the zones checked

Open in the tester

In each dialect

Every expression here is generated by the tester’s own engine and checked run for run against the others, so “Exact” means the same clock times in the same zone. Each one links to the tester.

Cron
0 0 1,15 * *
0 0 1,15 * * /path/to/command
  • Runs in the machine’s time zone. cronie also reads a CRON_TZ= line above the entry; other crons may not.
Exact
EventBridge
0 0 1,15 * ? *
aws events put-rule --name twice-a-month --schedule-expression "cron(0 0 1,15 * ? *)"
  • Wrap it in cron(…). Day of month is set (1,15), so day of week has to be ?. The final * is the required year field.
  • Scheduled rules always run in UTC. For local times, create it in EventBridge Scheduler with --schedule-expression-timezone.
Exact
Quartz
0 0 0 1,15 * ?
CronScheduleBuilder.cronSchedule("0 0 0 1,15 * ?")
  • The leading 0 is the seconds field, so it fires at the top of the minute. Day of month is set (1,15), so day of week has to be ?. The optional year is left off.
  • Uses the JVM’s default zone unless the trigger sets one with inTimeZone.
Exact
Kubernetes
0 0 1,15 * *
schedule: "0 0 1,15 * *"
  • Without timeZone under spec, these times are in the kube-controller-manager’s zone. A CRON_TZ= prefix in the schedule fails validation.
  • Kubernetes can occasionally create two Jobs for one scheduled time, or none, so make the job safe to repeat.
Exact
GitHub
0 0 1,15 * *
- cron: '0 0 1,15 * *'
  • GitHub warns that schedules can be delayed at high load, which includes the start of every hour, and that some queued jobs may be dropped. A different minute reduces the risk.
  • Times are UTC unless you add timezone: beside cron, with an IANA name.
  • In a public repository GitHub disables scheduled workflows after 60 days without repository activity, which is only about 4 runs of this schedule.
Exact
Azure
0 0 0 1,15 * *
[TimerTrigger("0 0 0 1,15 * *")]
  • Six fields with seconds first, so the leading 0 fires at the top of the minute.
  • UTC unless the app sets WEBSITE_TIME_ZONE, which Linux Consumption and Flex Consumption plans do not support.
Exact

About this schedule

A semi-monthly cycle, as for payroll: midnight on the 1st and the 15th. The gaps are uneven, 14 days then the rest of the month, because months are.

Clock changes

None of these times falls in the hour that clocks skip or repeat in New York, London, Berlin, Helsinki or Sydney, so every dialect runs it normally all year there. Zones that change clocks at other hours can still differ.

Questions

What is the cron expression for the 1st and 15th of the month?
0 0 1,15 * * in standard cron, Kubernetes and GitHub Actions. The other dialects differ: 0 0 1,15 * ? * in EventBridge; 0 0 0 1,15 * ? in Quartz; 0 0 0 1,15 * * in Azure.
Which time zone does it run in?
It depends on the scheduler. GitHub Actions, EventBridge rules and Azure use UTC unless you set a zone (timezone, EventBridge Scheduler’s --schedule-expression-timezone, WEBSITE_TIME_ZONE). Kubernetes uses .spec.timeZone or the controller manager’s zone, Quartz the JVM’s zone or inTimeZone, and cron the machine’s zone or CRON_TZ.

More schedules