Cron Expression Cheat Sheet¶

A quick reference for writing cron expressions used in scheduled tasks.

Cron 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)
│ │ │ │ │
* * * * *

Some systems (like AWS) add a 6th field for seconds at the start.

Special Characters¶

Character	Meaning	Example
`*`	Any value	`* * * * *` = every minute
`,`	List of values	`1,15,30` = at 1, 15, and 30
`-`	Range of values	`1-5` = 1 through 5
`/`	Step values	`*/15` = every 15 units

Common Examples¶

Every X Minutes¶

Expression	Description
`* * * * *`	Every minute
`/5 * * *`	Every 5 minutes
`/15 * * *`	Every 15 minutes
`/30 * * *`	Every 30 minutes

Every X Hours¶

Expression	Description
`0 * * * *`	Every hour (on the hour)
`0 /2 * *`	Every 2 hours
`0 /6 * *`	Every 6 hours
`30 * * * *`	Every hour at 30 minutes past

Daily¶

Expression	Description
`0 0 * * *`	Every day at midnight
`0 6 * * *`	Every day at 6:00 AM
`0 18 * * *`	Every day at 6:00 PM
`0 9,18 * * *`	Every day at 9 AM and 6 PM

Weekly¶

Expression	Description
`0 0 * * 0`	Every Sunday at midnight
`0 0 * * 1`	Every Monday at midnight
`0 9 * * 1-5`	Weekdays at 9:00 AM
`0 0 * * 6,0`	Weekends at midnight

Monthly¶

Expression	Description
`0 0 1 * *`	First day of every month at midnight
`0 0 15 * *`	15th of every month at midnight
`0 9 1 * *`	First day of every month at 9:00 AM
`0 0 1,15 * *`	1st and 15th of every month

Yearly¶

Expression	Description
`0 0 1 1 *`	January 1st at midnight
`0 0 1 /3 `	First day of every quarter

Day of Week Reference¶

Number	Day
0	Sunday
1	Monday
2	Tuesday
3	Wednesday
4	Thursday
5	Friday
6	Saturday

Some systems also accept SUN, MON, TUE, etc.

Month Reference¶

Number	Month
1	January
2	February
3	March
4	April
5	May
6	June
7	July
8	August
9	September
10	October
11	November
12	December

Some systems also accept JAN, FEB, MAR, etc.

Special Strings¶

Some systems support these shortcuts:

String	Equivalent	Description
`@yearly`	`0 0 1 1 *`	Once a year (Jan 1)
`@monthly`	`0 0 1 * *`	Once a month (1st)
`@weekly`	`0 0 * * 0`	Once a week (Sunday)
`@daily`	`0 0 * * *`	Once a day (midnight)
`@hourly`	`0 * * * *`	Once an hour
`@reboot`	-	At startup

Real-World Examples¶

Business Hours¶

# Every 15 minutes during business hours (9 AM - 5 PM, Mon-Fri)
*/15 9-17 * * 1-5

Nightly Backup¶

# Every night at 2:30 AM
30 2 * * *

Weekend Maintenance¶

# Saturdays at 3:00 AM
0 3 * * 6

End of Month¶

# Last day of month at 11:59 PM (use day 28 to be safe)
59 23 28 * *

Every Quarter¶

# First day of Jan, Apr, Jul, Oct at 6:00 AM
0 6 1 1,4,7,10 *

AWS CloudWatch / EventBridge¶

AWS uses a slightly different format with 6 fields (includes year):

cron(minutes hours day-of-month month day-of-week year)

Examples:

cron(0 12 * * ? *)        # Every day at 12:00 PM UTC
cron(0/15 * * * ? *)      # Every 15 minutes
cron(0 9 ? * MON-FRI *)   # Weekdays at 9:00 AM

Note: AWS uses ? for "no specific value" in day-of-month or day-of-week.

Tips¶

Test your expressions - Use a cron expression validator before deploying
Consider timezones - Cron typically runs in the server's timezone
Avoid midnight rush - Many jobs run at 0 0 * * *, consider offsetting
Be specific - 0 9 * * * is better than * 9 * * * (once vs 60 times)
Document your crons - Future you will thank present you