CRNCron Expression

Complete Cron Guide (5- and 6-field Formats)

A Cron expression is a time-based syntax used on Linux/Unix systems to schedule recurring tasks. The standard format has 5 fields (minute, hour, day, month, weekday), while dialects like Quartz add a leading seconds field for 6-7 total fields. This tool instantly translates any cron expression into a plain-English description.

Common Cron Expressions

Cron Dialect Differences (Vixie / POSIX / Quartz)

• Vixie cron (Linux standard): 5 fields, weekday 0 = Sunday
• Quartz (Java): 6-7 fields — leading seconds (0-59), optional year field
• AWS EventBridge: 6 fields (min/hr/day/month/weekday/year); day and weekday cannot both be specified
• systemd timer: Uses OnCalendar= syntax, not cron (e.g. Mon *-*-* 09:00:00)

Kubernetes CronJob and systemd timer

Kubernetes CronJobs use 5-field Vixie format in spec.schedule with UTC times. Set concurrencyPolicy: Forbid to prevent a new job starting before the previous one finishes. systemd timer's OnCalendar= offers superior timezone control and automatic retry on failure.

How to Use

1. Type a cron expression into the input (e.g. 0 9 * * 1).
2. Read the plain-English description that appears immediately below.
3. Click any Preset to instantly apply a common pattern.