Cron Next Run Calculator
Enter a five field cron expression and see the next ten times it will actually fire, computed minute by minute rather than guessed. Handles ranges, steps, lists and name aliases.
Last reviewed by the Radiatus Cloud team
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Reading a schedule is not the same as trusting it
Most cron explainers translate an expression into an English sentence. That is useful, but it does not answer the question that actually matters before a deploy: at what wall clock time will this next fire, and is the gap between runs what I expect. A sentence like "at minute 0 past every hour on every day of week 1 through 5" hides the fact that a schedule fires 120 times a week, or that it will not fire again for three weeks.
The day of month and day of week trap
Standard cron applies an unusual rule. When both the day of month field and the day of week field are restricted, the job runs when either matches, not when both match. So 0 0 13 * 5 fires on the thirteenth of every month and on every Friday, not only on Friday the thirteenth. This single rule is behind a large share of surprise executions, and it is invisible in any explanation that reads the fields one at a time.
How this calculator works
Rather than reasoning about the fields, it steps forward one minute at a time from the moment you press the button and tests each candidate against every field, exactly as a cron daemon does. Times are shown in your browser local time zone alongside the interval since the previous run, so an unintentionally dense or sparse schedule is obvious at a glance.
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Frequently Asked Questions
Which cron dialect is supported?
The standard five field format: minute, hour, day of month, month, day of week. Wildcards, lists, ranges, step values written as */n or a-b/n, and three letter month and day names are all accepted. Sunday may be written as 0 or 7.
Are @daily and @reboot shortcuts handled?
The named shortcuts @yearly, @annually, @monthly, @weekly, @daily, @midnight and @hourly are expanded to their five field equivalents. @reboot has no clock time at all, so no run times can be listed for it.
Which time zone are the results in?
Your browser local time zone. A server running the job will use its own zone, usually UTC, so confirm the crontab environment before trusting a time. The offset in use is shown above the results.
Does it support six field cron with seconds?
No. Six field expressions are a Quartz and Spring convention rather than Unix cron. Drop the seconds field to test the schedule here, and remember that the two dialects also differ in how the day of week field is numbered.
Why does my expression never fire?
Usually an impossible date combination such as 30 February, or a day of month value above the length of the selected month. The tool searches forward four years before reporting that no run exists.
Privacy & Security
Everything runs in your browser; nothing is uploaded.
How to Use
Paste a cron expression such as 0 3 * * 1-5 and press Calculate to list the next run times.
Disclaimer: This tool is provided "as is" without warranty of any kind. Results are for educational and utility purposes.
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