How to use
- 1Type a cron expression or start from one of the presets.
- 2Edit the fields — minute, hour, day of month, month, day of week, plus seconds if needed.
- 3Read the plain-English meaning, e.g. “Every 15 minutes, between 09:00 and 17:59, on Monday through Friday”.
- 4Check the next 10 run times in your local time zone before you deploy.
Cron syntax in five fields
A standard crontab line has five fields: minute (0–59), hour (0–23), day of month (1–31), month (1–12 or JAN–DEC) and day of week (0–7 or SUN–SAT, where both 0 and 7 mean Sunday). Each field accepts * (every value), lists (1,15), ranges (9-17) and steps (*/5 or 10-50/10). So 30 8 * * 1-5 runs at 08:30 on weekdays, 0 0 1 * * at midnight on the first of every month, and */5 * * * * every five minutes. The macros @hourly, @daily, @midnight, @weekly, @monthly, @yearly and @annually are expanded too; @reboot is recognized, but it has no schedule to show.
The day-of-month / day-of-week trap
When both the day-of-month and the day-of-week fields are restricted, standard cron runs the job when either one matches — not only when both do. 0 9 13 * 5 therefore runs at 09:00 on the 13th of every month and on every Friday, not just on Friday the 13th. The list of upcoming runs makes surprises like this visible before they reach production. An impossible schedule such as 0 0 30 2 * (February 30) is reported as never running.
Six fields, Quartz and time zones
Tick “6 fields” to add a leading seconds field, as used by Quartz and Spring’s @Scheduled. Quartz also numbers the days of the week 1–7 starting on Sunday and supports L, W and # (last, nearest weekday, nth weekday of the month); this tool evaluates standard crontab rules and shows a message when those Quartz-only characters appear. Run times are calculated in your browser’s time zone, while many servers and CI schedulers run cron in UTC — shift the times by your offset accordingly.
Frequently asked questions
What does */5 mean in cron?
Every 5 units of that field, starting from its lowest value. In the minute field, */5 runs at :00, :05, :10 and so on.
How do I run a cron job every day at midnight?
Use 0 0 * * * (or @daily). For 2:30 a.m. every day, use 30 2 * * *.
Is Sunday 0 or 7 in cron?
Both. Standard cron accepts 0 and 7 for Sunday; Monday is 1 and Saturday 6. Quartz differs: 1 is Sunday and 7 is Saturday.
Why are the next run times different from my server?
The list uses your browser’s time zone. If your server or scheduler runs in UTC, shift the times by your UTC offset.
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