Cron Expression Explainer
Translate any 5-field cron expression into plain English and preview the next 5 runs.
Quick answer: Cron Expression Explainer: translate any 5-field cron expression into plain English and preview the next 5 runs. Runs entirely in your browser, free, no signup.
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Cron's five fields — minute, hour, day-of-month, month, day-of-week — are compact but easy to misread, and this tool turns them back into a sentence plus the next five fire times so you can confirm intent before deploying a schedule. The most valuable check is that preview list: it catches the mistakes plain English glosses over.
The field that surprises people most is day-of-month combined with day-of-week. In standard cron these are ORed, not ANDed — 0 0 13 * 5 runs on the 13th and every Friday, not only on Friday the 13th. Watch the two step-pattern traps too: */5 in the minutes field means "every 5 minutes," but a bare number like 5 means "only at minute 5," and steps count from the start of the range, so 0-30/10 fires at 0, 10, 20 and 30.
This explainer targets the classic 5-field POSIX syntax. Quartz-style expressions that add a leading seconds field (six fields) or use tokens like L, W and # won't parse here — those are extensions to the standard, not part of it.
Cron itself carries no time zone, so the previewed runs are shown in UTC for unambiguous comparison; translate them to a local wall clock with the Timezone Converter, keeping daylight-saving shifts in mind if your scheduler runs in local time.
Frequently asked questions
- Is the cron explainer free?
- Yes — free with no signup.
- Which cron flavor?
- Standard 5-field POSIX cron (minute, hour, day, month, weekday). 6-field 'seconds-first' cron used by Quartz isn't supported.
- Are my expressions uploaded?
- No — every parse runs in your browser.
- What about ranges and step values?
- Ranges (1-5), lists (1,3,5) and steps (*/15) are supported — they round-trip through cron-parser correctly.
- Why are the next runs in UTC?
- Cron schedules don't carry a time zone. Showing them in UTC makes comparisons unambiguous; convert to local with our Timezone Converter.