Cron expressions define schedules for automated tasks. Originally from Unix cron, they're now used everywhere — Kubernetes CronJobs, GitHub Actions, AWS EventBridge, CI/CD pipelines, and task schedulers in virtually every programming language.

Anatomy of a Cron Expression

A standard cron expression has 5 fields:

┌───────────── minute (0-59)

│ ┌───────────── hour (0-23)

│ │ ┌───────────── day of month (1-31)

│ │ │ ┌───────────── month (1-12)

│ │ │ │ ┌───────────── day of week (0-6, 0=Sunday)

│ │ │ │ │

* * * * *

Some systems add a 6th field for seconds at the beginning.

Special Characters

* — any value (wildcard)

, — list separator: 1,15 means "1 and 15"

- — range: 1-5 means "1 through 5"

/ — step: */5 means "every 5"

? — no specific value (used in some systems for day-of-month or day-of-week)

L — last (e.g., L in day-of-month = last day of month)

W — weekday nearest to the given day

# — nth occurrence (e.g., 5#2 = second Friday)

Common Schedule Examples

Every minute

* * * * *

Every 5 minutes

*/5 * * * *

Every hour (at minute 0)

0 * * * *

Every day at midnight

0 0 * * *

Every day at 9:30 AM

30 9 * * *

Every Monday at 8 AM

0 8 * * 1

Every weekday at 6 PM

0 18 * * 1-5

First day of every month at noon

0 12 1 * *

Every 15 minutes during business hours (9-5, Mon-Fri)

*/15 9-17 * * 1-5

Every quarter (Jan 1, Apr 1, Jul 1, Oct 1) at midnight

0 0 1 1,4,7,10 *

Twice a day (8 AM and 8 PM)

0 8,20 * * *

Platform-Specific Shorthand

Some platforms support predefined schedules:

@yearly or @annually — 0 0 1 1 *

@monthly — 0 0 1 * *

@weekly — 0 0 * * 0

@daily or @midnight — 0 0 * * *

@hourly — 0 * * * *

Common Mistakes

Confusing day-of-week numbering (0 = Sunday in standard cron, 1 = Monday in some systems)

Forgetting that both day-of-month AND day-of-week are checked (OR logic, not AND)

Setting */5 in the hour field thinking it runs every 5 minutes (it runs every 5 hours)

Not accounting for timezone differences on servers

Overlapping schedules when combining ranges and lists

Debugging Tips

Always verify your expression with a parser before deploying

Check the next 5-10 execution times to confirm the schedule is correct

Consider timezone — most cron engines use server local time or UTC

Start with verbose schedules and simplify once tested

Parse and validate your cron expressions with our Cron Expression Parser.

Cron Expressions Explained — Syntax, Examples & Common Schedules