Run a Cron Job Every 30 Minutes
*/30 fires twice an hour, at :00 and :30. It's effectively shorthand for 0,30 in the minute field, and the last stop before hourly scheduling — good for digest emails, moderately fresh dashboards, and batch syncs.
*/30 * * * *In plain English: Every 30 minutes.
Field by field
| Field | Value | Meaning |
|---|---|---|
| Minute | */30 | every 30 minutes |
| Hour | * | every hour |
| Day of month | * | every day |
| Month | * | every month |
| Day of week | * | every weekday |
Variations
15,45 * * * *twice an hour at :15 and :45 — offset from the hour*/30 6-22 * * *every 30 minutes during waking hours only0 * * * *reduce to once an hourTweak any of these in the crontab explainer to see the schedule in plain English and its next run times.
Frequently asked questions
Is */30 the same as 0,30?
Yes. A step of 30 over the 0–59 range lands on exactly 0 and 30. Both fire twice per hour.
How do I run every 45 minutes?
You can't express a true 45-minute cadence in one standard cron line, because the minute field resets each hour. Either use two entries covering alternating patterns, or schedule every 15 minutes and let the job itself decide whether to act.
New to cron syntax? Read Cron Expressions Explained, Field by Field.