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Cron job every 30 minutes

Every half hour is */30 * * * *: on the hour and at half past, 48 times a day. 0,30 * * * * means the same and is often easier to read.

*/30 Minute 0-59
* Hour 0-23
* Day 1-31
* Month 1-12
* Weekday 0-7

Open and adjust in the crontab generator ›

Meaning

What the expression says exactly

The slash divides the minute range 0 to 59 into steps of 30. That leaves minutes 0 and 30. The other fields are *, so the job runs every hour, every day.

With a list you can shift the interval freely: 10,40 * * * * runs every half hour just the same, only at ten past and twenty to.

The next runs

  • Sat, 14 Nov 2026, 01:30
  • Sat, 14 Nov 2026, 02:00
  • Sat, 14 Nov 2026, 02:30
  • Sat, 14 Nov 2026, 03:00
  • Sat, 14 Nov 2026, 03:30

Calculated in German time when this page was loaded.

Variants

Similar schedules

10,40 * * * * Every half hour, away from the full and the half hour. Adjust
*/30 9-17 * * 1-5 Every 30 minutes on weekdays from 9:00 to 17:30. Adjust
15,45 8-17 * * * Every half hour from 8:15, the last run at 17:45. Adjust
0 * * * * Half as often: hourly on the hour. Adjust

Watch out for

Typical mistakes with this interval

30 * * * * is hourly

Without the slash, the 30 stands only for minute 30. The job then runs once an hour at half past, not twice.

Every 45 minutes does not work this way

*/45 runs at minute 0 and 45 of every hour. The gaps therefore alternate between 45 and 15 minutes. A true 45-minute interval shifts every hour and does not fit into one crontab line. If you need it, run the job every 15 minutes and let the script check whether 45 minutes have passed since the last run.

Cron has no start time

If the job should start at 8:15 and then run every 30 minutes, write out the times: 15,45 8-17 * * *. The crontab has no starting point to count from, only clock times that have to match.

Own server

How it looks in the crontab

Open with crontab -e and add one line. The first starts a PHP script directly, the second calls an address. Replace paths and address with your own.

*/30 * * * * /usr/bin/php /pfad/zu/skript.php >/dev/null 2>&1
0,30 * * * * curl -fsS https://ihre-domain.de/cron.php >/dev/null

Without your own server

How it works at Cronjob.de

No command-line access needed: you enter the address of your script and click the schedule together. You can also type the expression above directly, or describe the interval in one sentence and have it suggested. Cronjob.de uses German time.

Five cronjobs are free forever, on the five-minute grid. One-minute intervals start with Plus. How to prepare a script on shared web space for this is explained in the web space guide.

FAQ

Common questions

Which is better, */30 or 0,30?
In effect both are the same. The list is easier to read and easier to shift, for example to 15,45.
Is every half hour possible on the free plan?
Yes, as long as the minutes are divisible by five. 0,30, 10,40 and 15,45 all work.
How do I run a job every two hours?
With 0 */2 * * *: on the hour at 0, 2, 4 … 22. Here the slash is in the hour field.

Create your cronjob now

Create an account, enter the address, click the schedule. Five cronjobs are free forever, the first 14 days run on the Unlimited plan.

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