How do I schedule a job every 3 hours?

Use the cron expression 0 */3 * * *. You can set this in crontab on Linux, or use a service like CronJobPro to schedule HTTP requests with this expression.

Interval Schedules

Cron Job Every 3 Hours – Expression & Examples

The */3 step in the hour field triggers at hours 0, 3, 6, 9, 12, 15, 18, and 21 — 8 times per day.

Cron Expression

0 */3 * * *

Minute

(0-59)

*/3

Hour

(0-23)

Day of Month

(1-31)

Month

(1-12)

Day of Week

(0-6)

How It Works

The */3 step in the hour field triggers at hours 0, 3, 6, 9, 12, 15, 18, and 21 — 8 times per day.

Common Use Cases

Social media posting
Weather data collection
Database optimization

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Frequently Asked Questions

What does `0 /3 * *` mean in cron?

The */3 step in the hour field triggers at hours 0, 3, 6, 9, 12, 15, 18, and 21 — 8 times per day.

How do I use this cron expression?

On Linux/macOS, edit your crontab with crontab -e and add:
0 */3 * * * /path/to/your/script.sh
Or use CronJobPro to schedule HTTP requests with this expression — no server required.

What timezone does cron use?

By default, cron uses the system timezone. CronJobPro lets you set a specific timezone per job, so your schedules are predictable regardless of server location.