Cron HelperCron expression for every 30 minutes
Every 30 minutes.
Five fields for Linux, GitHub Actions and Kubernetes (minute hour day month weekday). Six or seven for Quartz. Nothing you type leaves your device.
What it means and when to use it
Half-hourly runs fit tasks that are worth doing often but not constantly: updating exchange rates, refreshing a sitemap, polling an API with a daily quota, or sending a reminder summary. Two runs an hour is 48 a day.
Watch out for this
Step values never carry over from one hour to the next. */30 means minute 0 and minute 30 of every hour, which happens to be exactly 30 minutes apart. But */45 does not mean every 45 minutes: it means minutes 0 and 45 of every hour, so the gaps are 45 minutes and then 15 minutes. If your interval does not divide 60 evenly, see the page on cron step values for the workaround.
What each field says
| Field | Written | Means |
|---|---|---|
| Minute | */30 | 0, 30 |
| Hour | * | every hour |
| Day of month | * | every day of the month |
| Month | * | every month |
| Day of week | * | every day of the week |
An example of the next runs
If it were Friday 13 November 2026 at 10:20 UTC, the next six runs would be these. Times are shown in UTC and in India time (UTC+5:30).
| UTC | India time |
|---|---|
| Fri 13 Nov, 10:30 | Fri 13 Nov, 16:00 |
| Fri 13 Nov, 11:00 | Fri 13 Nov, 16:30 |
| Fri 13 Nov, 11:30 | Fri 13 Nov, 17:00 |
| Fri 13 Nov, 12:00 | Fri 13 Nov, 17:30 |
| Fri 13 Nov, 12:30 | Fri 13 Nov, 18:00 |
| Fri 13 Nov, 13:00 | Fri 13 Nov, 18:30 |
The same schedule in other places
Quartz
Quartz has a seconds field in front, uses ? in one day field, and counts Sunday as 1:
0 */30 * * * ?GitHub Actions
Scheduled workflows run in UTC unless you add a time zone. In the workflow file:
on:
schedule:
- cron: '*/30 * * * *'Kubernetes CronJob
In a CronJob manifest the schedule goes in spec.schedule. Without spec.timeZone, it is read in the time zone of the cluster's controller:
spec:
schedule: "*/30 * * * *"
timeZone: "Etc/UTC"A crontab line to copy
The command is made up. Replace it with your own and use full paths:
*/30 * * * * /usr/bin/python3 /home/me/rates/update.py >> /home/me/rates/log.txt 2>&1Questions
Is */30 the same as 0,30?
Yes. Both mean minute 0 and minute 30.
This is an independent guide and tool. It is not connected with crontab.guru, Quartz, GitHub, Kubernetes, Spring or the Linux projects named here. Product names belong to their owners.