Cron Expression Syntax: A Complete Guide

Master cron expressions: field breakdown, special characters, and common schedule examples.

Last updated: 2026-03-05

A cron expression is a string of 5 (or 6) fields that defines a recurring schedule for running automated tasks. It is the standard format used in Unix cron jobs, CI/CD pipelines, cloud schedulers (AWS EventBridge, GitHub Actions), and most backend job frameworks.

Field Layout

text

┌─────────── minute        (0–59)
│ ┌───────── hour          (0–23)
│ │ ┌─────── day of month  (1–31)
│ │ │ ┌───── month         (1–12 or JAN–DEC)
│ │ │ │ ┌─── day of week   (0–6 or SUN–SAT, 0=Sunday)
│ │ │ │ │
* * * * *

Some systems add a 6th field for seconds (Quartz, Spring) at the beginning, or a 6th year field at the end.

Special Characters

Character	Name	Meaning
*	Wildcard	Every value in the field
,	List	Multiple values: 1,3,5
-	Range	A range of values: 1-5
/	Step	Every N values: */5 = every 5 minutes
L	Last	Last day of month or week (some implementations)
W	Weekday	Nearest weekday to given day (some implementations)
#	Nth	3rd Monday = MON#3 (some implementations)

Common Schedule Examples

* * * * *Every minute

*/5 * * * *Every 5 minutes

0 * * * *Every hour (at :00)

0 */2 * * *Every 2 hours

0 9 * * *Daily at 9:00 AM

0 0 * * *Daily at midnight

0 9 * * MON-FRIWeekdays at 9:00 AM

0 9 * * 1Every Monday at 9:00 AM

0 0 1 * *First day of every month at midnight

0 0 1 1 *Once a year on January 1st at midnight

30 8 * * 1-5Weekdays at 8:30 AM

0 0,12 * * *Twice daily: midnight and noon

0/30 * * * *Every 30 minutes (Quartz syntax)

Month and Day Names

Months

Number	Name
1	JAN
2	FEB
3	MAR
4	APR
5	MAY
6	JUN
7	JUL
8	AUG
9	SEP
10	OCT
11	NOV
12	DEC

Days of Week

Number	Name
0 (or 7)	SUN
1	MON
2	TUE
3	WED
4	THU
5	FRI
6	SAT

Platform Differences

Watch out: AWS EventBridge and Quartz use a 6-field syntax with seconds as the first field. GitHub Actions uses standard 5-field cron but runs in UTC. Some systems treat 0 and 7 as Sunday for day-of-week. Always check your platform's documentation.

Parse and explain any cron expression with the Cron Expression Parser tool.

Frequently Asked Questions

What does * mean in a cron expression?

The asterisk (*) means "every possible value" for that field. For example, * in the hour field means "every hour", and * in the day-of-week field means "every day of the week".

How do I run a cron job every 5 minutes?

Use the expression */5 * * * *. The */5 in the minute field means "every 5th minute". The asterisks in the remaining fields mean every hour, every day, every month, every weekday.

What is the cron expression for daily at midnight?

Use 0 0 * * * to run at midnight (00:00) every day. The first 0 is the minute field and the second 0 is the hour field.

What is the difference between cron and crontab?

cron is the daemon (background service) that executes scheduled tasks. crontab is the command and file format used to create, edit, and manage the schedule entries that cron reads.

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