Cron Next Run Times

What the next-run calculation does

Given a cron expression, this tool computes the upcoming fire times so you can confirm a schedule means what you think. A standard cron line has five fields, minute, hour, day of month, month, and day of week, and the tool walks forward from now, matching each field, to list the next several moments the job would run.

When you reach for it

You use it before deploying a scheduled job, when a job fired at an unexpected time, or when translating a plain-English schedule like "every weekday at 6am" into fields you can trust. Seeing three or four concrete timestamps catches mistakes an expression alone hides.

Example

30 6 * * 1-5    "At 06:30 on Mon-Fri"

Next runs:
  Mon 2024-06-03 06:30
  Tue 2024-06-04 06:30
  Wed 2024-06-05 06:30

Fields are minute, hour, day-of-month, month, day-of-week. Here minute 30, hour 6, any day, any month, weekdays 1 through 5.

Common pitfalls

The notorious trap is the day-of-month and day-of-week relationship. When both fields are restricted (neither is *), cron treats them as an OR, not an AND. So 0 0 1 * 1 runs on the 1st of the month and on every Monday, not only on a Monday that happens to be the 1st. People expect AND and get surprised by extra runs. The second pitfall is timezone: plain cron fires in the server's local time, so a daylight saving shift can make a job skip or double a run around the changeover. For a cloud scheduler, note the different format in the EventBridge converter, and for plain-English readings see crontab describe.

FAQ

Why does my job run on days I did not expect? Likely the day-of-month OR day-of-week rule firing on both conditions. Leave one field as * to avoid it.

What timezone are the runs in? Standard cron uses the host's local time unless the daemon is configured otherwise, so confirm the server clock.

What does */15 mean? A step: every 15 units from zero, so minutes 0, 15, 30, 45.