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Cron Reference

Every 3 Hours

Runs 8 times per day at midnight, 3 AM, 6 AM, 9 AM, noon, 3 PM, 6 PM, and 9 PM.

Cron Expression

0 */3 * * * Test in tool

Every 3 hours

Expression Breakdown

Minute Hour Day Month Weekday
0 */3 * * *
0 every 3 any any any

Next 5 Scheduled Runs

  • Saturday, June 13 2026 at 9:00 PM
  • Sunday, June 14 2026 at 12:00 AM
  • Sunday, June 14 2026 at 3:00 AM
  • Sunday, June 14 2026 at 6:00 AM
  • Sunday, June 14 2026 at 9:00 AM

Times are relative to the server's local clock at page load.

Common Use Cases

  • Social media scheduled posting
  • Data synchronisation
  • Summary report generation

How to Install

Linux / macOS (crontab)

Run crontab -e and add this line:

0 */3 * * * /path/to/your/script.sh

Python (APScheduler / cron-style)

scheduler.add_job(my_func, 'cron',
    minute='0',
    hour='*/3',
    day='*',
    month='*',
    day_of_week='*')

GitHub Actions (schedule)

on:
  schedule:
    - cron: '0 */3 * * *'

Frequently Asked Questions

When exactly does 0 */3 * * * run?
00:00, 03:00, 06:00, 09:00, 12:00, 15:00, 18:00, 21:00 — every 3 hours starting from midnight.