What is the cron expression for every 3 hours?

The expression is 0 */3 * * *. It runs at 0:00, 3:00, 6:00, 9:00, 12:00, 15:00, 18:00, 21:00.

SimpleCronTab

Cron Every 3 Hours

0 */3 * * *

Every 3 hours

Next 10 Executions

Times shown in UTC

Mon, May 18, 202609:00
Mon, May 18, 202612:00
Mon, May 18, 202615:00
Mon, May 18, 202618:00
Mon, May 18, 202621:00
Tue, May 19, 202600:00
Tue, May 19, 202603:00
Tue, May 19, 202606:00
Tue, May 19, 202609:00
Tue, May 19, 202612:00

Field Breakdown

0

Minute

*/3

Hour

Every 3 hours

*

Day of Month

Every day

*

Month

Every month

*

Day of Week

Every day of week

About This Schedule

The cron expression 0 */3 * * * runs a job every 3 hours — at 12:00 AM, 3:00 AM, 6:00 AM, 9:00 AM, 12:00 PM, 3:00 PM, 6:00 PM, and 9:00 PM. That's 8 executions per day.

Since 24 divides evenly by 3, the intervals are perfectly uniform across the day. This is a good interval for tasks like digest emails, periodic data syncs, and batch processing jobs.