Cron example
Cron Every 30 Minutes
Two runs an hour, at :00 and :30, forty-eight times a day. The step form and the explicit list 0,30 produce exactly the same schedule, and cron treats them identically — the list version is simply easier for the next person to read at a glance in a crowded crontab.
By NaveenKumar T · Updated · 5-field crontab expression
What each field means
| Field | Value | Meaning |
|---|---|---|
| Minute | */30 | Every 30 minutes, starting at minute 0 |
| Hour | * | Every hour |
| Day of month | * | Every day |
| Month | * | Every month |
| Day of week | * | Every day of the week |
Next 5 run times
Computing the next runs in your timezone…
The half-hour sweet spot
Half-hourly is where jobs land when hourly is a little too coarse to satisfy a stakeholder but every five minutes would be theatre. Typical residents: mailbox and ticket syncs, currency or pricing refreshes, partial index updates, and dashboards fed by a warehouse that only lands new data a few times an hour anyway.
It is also a good fit for anything with a two-to-ten-minute runtime. There is real headroom before the next start, so an occasional slow run does not collide, and you still get 48 opportunities a day to notice something has broken. Compare that with a daily job, where a failure can sit unnoticed for 24 hours.
Off-the-hour and half-open variants
If the top of the hour is congested — hourly jobs, log rotation and monitoring sweeps all tend to cluster at :00 — shift the pair with 5,35 * * * *. That is still exactly thirty minutes apart, just phase-shifted away from the crowd. The same trick works with the step syntax written as 5-59/30, though the explicit list is clearer.
To spread the load hour by hour, restrict the hour field instead of the minute field: 0,30 8-20 * * * runs half-hourly only between 8 AM and 8 PM, which is 26 runs instead of 48. And if you decide half-hourly was overkill after all, every hour is the next step down, with every 2 hours after that.
Build a variant of this schedule with dropdowns and check the next ten runs before you install it.
Open the cron generatorRelated cron examples
Browse every schedule on the cron expression generator, read the cron expression syntax guide for the rules behind the five fields, or the developer tools guides for the longer explanations.