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Cron Expression Explainer & Next Run Calculator
Decode any 5-field cron expression and see its next scheduled run times.
About this tool
Cron expressions are compact, but they are easy to get wrong: a single misplaced asterisk can turn a nightly backup into a job that fires every minute. This tool parses a standard five-field cron expression (minute, hour, day of month, month, day of week), explains what each field matches, and calculates the next five times the schedule will actually fire in your local time zone.
It supports wildcards, lists (1,15), ranges (9-17), steps (*/10 and 0-30/5), month and weekday names (JAN, MON-FRI) and the common shortcuts @hourly, @daily, @weekly, @monthly and @yearly. It also follows the classic Vixie-cron rule: when both day-of-month and day-of-week are restricted, the job runs when either matches.
Everything is calculated in your browser, so you can safely test expressions that belong to private servers.
How to use it
- Type or paste a cron expression, or click one of the presets.
- Press Explain.
- Read the field-by-field breakdown and check the upcoming run times match what you intended.
Frequently asked questions
Does this support seconds or year fields?
No. It targets the standard five-field format used by Linux crontab, most hosting panels and many schedulers. Quartz-style six or seven field expressions are not supported.
Which time zone are the next runs shown in?
Your browser's local time zone. A real server may run in UTC, so convert accordingly before relying on the times.
Why does my day-of-month and weekday combination run more often than expected?
In classic cron, if both fields are restricted the job fires when either one matches, not only when both do.
Results are provided for general information. Please read our disclaimer.