Run a Cron Job Every Half Hour
To run a job every half hour, use */30 * * * *. It fires at minute 0 and minute 30 of every hour — twice an hour, 48 times a day. The expression 0,30 * * * * does exactly the same thing.
The expression
*/30 * * * * runs at :00 and :30 of every hour. The */30 step means 'every 30 minutes' within the 0–59 minute range.
Same thing, written out
0,30 * * * * is identical — it lists the two minutes explicitly. Use whichever you find clearer.
Limit to certain hours
Every half hour during the day only: */30 9-17 * * * runs on the hour and half-hour from 9 AM to 5 PM.
FAQ
What is the cron expression for every half hour?
*/30 * * * * runs at minute 0 and minute 30 of every hour — twice an hour.
Is */30 the same as 0,30?
Yes. 0,30 * * * * and */30 * * * * both fire on the hour and at half past. Pick whichever reads better to you.
How do I run every half hour only during work hours?
Use */30 9-17 * * * to fire on the hour and half-hour between 9 AM and 5 PM.