Format
5 fields: minute hour day month weekday
Try an example
Upcoming executions
Why Preview Next Runs?
A cron expression can be syntactically valid but fire at unexpected times.
The classic example is 30 4 1,15 * 5 - most people expect it to run on the 1st and 15th of the month, but only when those days are Fridays.
In Linux cron, it runs on the 1st, the 15th and every Friday, because day-of-month and day-of-week use OR logic.
Previewing the next 10 or 20 runs makes this kind of surprise immediately obvious.
Timezone Note
All run times are calculated in your browser's local timezone. On a real server, cron uses the server's system timezone.
| Platform | Timezone |
|---|---|
| Linux cron | Server system TZ |
| Kubernetes | Node system TZ |
| AWS EventBridge | Always UTC |
| Quartz / Spring | Application TZ |
Common Surprises
30 4 1,15 * 5
Runs on the 1st, the 15th AND every Friday - not "the 1st/15th if it is a Friday". Linux cron ORs day-of-month and day-of-week when both are set.
0 0 31 * *
Only fires in months that have 31 days (Jan, Mar, May, Jul, Aug, Oct, Dec). Never fires in February, April, June, September or November.
0 0 29 2 *
Only fires on February 29th - so once every four years, on leap years. If you mean "last day of February", this is not the right expression.
* * * * *
Runs every minute, every hour, every day. 1,440 times per day. If your backup script takes more than a minute, you will have overlapping runs by the second execution.