Cron Expression Parser

Debug standard 5-field cron expressions with safe presets, a deterministic share URL, field-by-field explanations, and an upcoming-run timeline.

Expression Input
Clear
Schedule summary

Previewed this 5-field cron schedule in Asia/Seoul and expanded the next 5 matching runs for quick debugging.

Expression 0 9-17 * * 1-5
Preview timezone Asia/Seoul (KST)
Evaluated from Wed, Jul 15, 2026 21:44 KST
Reference UTC 2026-07-15 12:44 UTC
Share URL https://comutil.com/cron?preset=weekday-business-hours
Next 5 Runs
Run 1 Thu, Jul 16, 2026 09:00 KST
UTC 2026-07-16 00:00 UTC
Relative 11 hours from now
Run 2 Thu, Jul 16, 2026 10:00 KST
UTC 2026-07-16 01:00 UTC
Relative 12 hours from now
Run 3 Thu, Jul 16, 2026 11:00 KST
UTC 2026-07-16 02:00 UTC
Relative 13 hours from now
Run 4 Thu, Jul 16, 2026 12:00 KST
UTC 2026-07-16 03:00 UTC
Relative 14 hours from now
Run 5 Thu, Jul 16, 2026 13:00 KST
UTC 2026-07-16 04:00 UTC
Relative 15 hours from now
Field-by-Field Breakdown
Minute
0
Allowed range 0-59
Meaning Matches 00.
Hour
9-17
Allowed range 0-23
Meaning Matches 09 through 17.
Day of month
*
Allowed range 1-31
Meaning Matches every allowed value.
Month
*
Allowed range 1-12 or JAN-DEC
Meaning Matches every allowed value.
Day of week
1-5
Allowed range 0-7 or SUN-SAT
Meaning Matches Monday through Friday.
Use the live cron parser, then continue the automation review

Stay on this page for the schedule preview itself, then jump into the matching guide or the related regex, Markdown, and diff explainers when the task expands.

Read the cron guide Open Automation/Text Ops hub
Automation/Text Ops hub
Return to the cluster chooser for cron, regex, Markdown, and diff workflows.
Regex validation guide
Switch to regex when the scheduled task fails because of pattern matching, not timing.
Markdown preview guide
Document the schedule in a browser-first runbook once the timing is correct.
Diff review guide
Compare old and new cron config once you know which field changed.
Debugging Presets
Weekday business hours
Active
Preview top-of-the-hour jobs during a Monday-to-Friday business-hours window.
0 9-17 * * 1-5
Every 5-minute polling
Preset
Check a steady polling or queue-drain cadence without carrying any private state.
*/5 * * * *
Overnight backup
Preset
Inspect a single nightly backup run before you move it into production scheduler configs.
30 2 * * *
Weekend maintenance
Preset
Review a weekend-only maintenance window that stays out of weekday traffic.
0 4 * * 6,0
What is a Cron Expression?

A cron expression is a string consisting of five or six fields that define a schedule for running automated tasks. Originally from Unix cron daemon, this syntax is now used in many scheduling systems. Each field represents a time unit: minute, hour, day of month, month, day of week, and optionally year.

Cron Field Format

Standard cron has 5 fields: minute (0-59), hour (0-23), day of month (1-31), month (1-12), day of week (0-6, Sunday=0). Special characters include: * (any), , (list), - (range), / (step). Extended formats may include seconds and year fields.

Common Use Cases
  • Scheduling backup jobs
  • Running periodic data synchronization
  • Sending scheduled emails or notifications
  • Clearing temporary files and caches
  • Generating periodic reports
Common Patterns
Input: 0 0 * * *
Output: Every day at midnight
Input: */15 * * * *
Output: Every 15 minutes
Input: 0 9 * * 1-5
Output: Every weekday at 9 AM
Input: 0 0 1 * *
Output: First day of every month at midnight
Frequently Asked Questions

What timezone does cron use?

Traditional cron uses the system timezone. Modern schedulers like Kubernetes CronJobs let you specify the timezone. Always verify which timezone your cron system uses.

How do I run a job every second?

Standard 5-field cron doesn't support seconds (minimum is every minute). Some systems like Quartz support 6-field cron with seconds. Alternatives include using sleep loops or task schedulers designed for sub-minute intervals.