Cron Expression Explainer
Decode minute–hour–dom–month–dow schedules, see what they mean, and preview the next runs in your timezone.
Unix 5-field cron (minute hour day-of-month month day-of-week). Plain English, field decode, next 10 runs in your timezone — nothing is uploaded.
How to use this tool
- Paste a 5-field Unix cron expression (or pick a preset / nickname like @daily).
- Read the plain-English meaning and the per-field breakdown.
- Choose a timezone (Local or UTC shortcuts) and copy the next run times if you need them for a PR or runbook.
Debug schedules before they page you
Crontab lines, Kubernetes CronJobs, GitHub Actions schedule, and Vercel crons still speak five terse fields. A single off-by-one in day-of-week or a forgotten timezone turns “weekdays at 9” into weekend noise. This tool is the paste-and-check loop: English sentence, field decode, and the next ten fire times in the zone your servers actually use.
Need epoch math for those run timestamps? Try the Unix Timestamp Converter. Comparing wall times across regions? Use the Timezone Converter.
FAQ
Is my cron expression uploaded?
No. Parsing, English description, and next-run calculation all run in your browser. Schedules never leave your device.
Which cron format is supported?
Unix / Vixie 5-field cron: minute hour day-of-month month day-of-week. Also standard nicknames (@hourly, @daily, @midnight, @weekly, @monthly, @yearly / @annually). Quartz/Spring extras (?, L, W, #) and 6–7 field forms are rejected on purpose.
Why do day-of-month and day-of-week both matter?
If both are restricted (not *), classic Unix cron fires when either field matches — OR logic, not AND. This tool warns when that applies and uses the same OR behavior for next runs.
Are next run times timezone-accurate?
Yes. Pick any IANA zone (or jump to Local / UTC). Calculations use that zone, including daylight-saving transitions. Missing local times (spring-forward gaps) may shift — the same class of edge case every scheduler hits.
Is Sunday 0 or 7?
Both. In Unix cron, 0 and 7 mean Sunday. Names SUN–SAT work too. Monday is 1.
Does @reboot work?
No. @reboot is a startup event, not a clock schedule, so there is nothing meaningful to preview as “next runs.”