How it works

Five fields: minute  hour  day-of-month  month  day-of-week (0-59, 0-23, 1-31, 1-12, 0-7 — where both 0 and 7 mean Sunday). Fields accept *, single numbers, comma-separated lists, inclusive ranges like 9-17, and steps like */5 or 1-15/3. The shortcut forms @yearly, @annually, @monthly, @weekly, @daily, @midnight and @hourly are expanded and explained.

The day-of-month / day-of-week quirk

If both day fields are restricted (neither is * nor starts with it), cron runs the job when either matches — the union. If either field is * or a *-step like */2, the fields combine with and. This tool flags which case applies and why, exactly as the classic cron implementations behave.

What it does not do

No future-run preview and no timezone or DST handling — when a job fires next depends on the scheduler's timezone, and explaining that belongs to the machine running the schedule. Month and weekday names (JAN, MON) are valid cron but not supported by this tool; use numbers. Six- or seven-field expressions are the Quartz/Spring dialect, not Unix cron.

Privacy

Explanation happens entirely in your browser. Nothing is transmitted, logged, or stored — you can disconnect from the internet and keep using this page.

FAQ

Related tools

JSON formatter — cron fields are comma-separated lists, much like JSON arrays; validate and inspect the JSON your scheduler emits.

JWT decoder — scheduled jobs often authenticate with bearer tokens; decode one to check its expiry claims before wiring it into cron.