Cron Expression: 1st and 15th of the Month
The expression is 0 0 1,15 * *. Paste it above to read it in English and preview the next run times. Common for payroll and semi-monthly jobs.
The expression
0 0 1,15 * * runs a job at midnight on the 1st and the 15th of every month — the classic semi-monthly (payroll) schedule.
Field by field
0 0 is midnight; 1,15 is a day-of-month list; the remaining * * mean every month, any weekday.
Why not “every 15 days”
People often want “every two weeks”, but 1,15 is not exactly 15 days apart — gaps range from 13 to 17 days depending on month length. That's usually what payroll wants; true 14-day cycles need a different approach.
Variations
1st and 15th at 9am: 0 9 1,15 * *.
FAQ
What does 0 0 1,15 * * do?
Runs the job at midnight on the 1st and 15th of every month.
Is the 1st-and-15th the same as every 15 days?
No. Gaps range from 13 to 17 days depending on the month, because month lengths vary.
How do I run it at 9am instead of midnight?
Use 0 9 1,15 * *.