Cron Approximately Every 90 Minutes
Schedule a cron job approximately every 90 minutes using 0,30 */3 * * *. Field-by-field explanation with timing details and scheduling advice.
Cron Expression
0,30 */3 * * *
Field Breakdown
| Field | Value | Meaning |
|---|---|---|
| Minute | 0,30 | At 0, 30 |
| Hour | */3 | Every 3rd hour |
| Day of Month | * | Every day of the month (1–31) |
| Month | * | Every month (1–12) |
| Day of Week | * | Every day of the week (Sun–Sat) |
Detailed Explanation
The cron expression 0,30 */3 * * * approximates a 90-minute interval by running at minutes 0 and 30 of every third hour throughout the day.
Field-by-field breakdown:
0,30(Minute): At minutes 0 and 30. The list notation specifies two exact minutes within each qualifying hour when the task will execute.*/3(Hour): Every 3rd hour, starting from hour 0. The step value/3restricts execution to hours 0, 3, 6, 9, 12, 15, 18, and 21.*(Day of Month): Every day from 1 through 31. No restriction on the day of the month.*(Month): Every month from January through December. No restriction on which month.*(Day of Week): Every day of the week from Sunday through Saturday. No restriction on the day of the week.
This means your task will execute at 0:00, 0:30, 3:00, 3:30, 6:00, 6:30, and so on, for a total of 16 executions per day. The intervals alternate between 30 minutes and 150 minutes rather than a uniform 90 minutes. Standard cron cannot express a true 90-minute cycle because 90 does not divide evenly into 60 minutes or 24 hours. If you need exact 90-minute spacing, consider using a systemd timer or an external scheduler. This expression is supported by standard cron on Linux/macOS, as well as cloud services like AWS CloudWatch, Google Cloud Scheduler, and GitHub Actions.
Use Case
Suitable for periodic data synchronization between systems where you need roughly every-90-minute updates without requiring precise interval timing.
Try It — Interactive Builder
at min 0,30, every 3h
Next 10 Executions
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