SyntaxReference8 min read

Cron Expression Syntax: Every Field Explained

A complete reference for cron expression syntax — all five fields, special characters, step values, and the most common gotchas that trip up experienced developers.

The Anatomy of a Cron Expression

A standard cron expression has exactly 5 fields, separated by spaces. Each field controls a specific aspect of when the job runs.

* * * * *

Minute 0–59

Hour 0–23

Day of Month 1–31

Month 1–12

Day of Week 0–7

Quick example: 30 9 * * 1-5 = At 9:30 AM, Monday through Friday.

The 5 Cron Fields

Minute— range: 0–59

Which minute(s) of the hour the job runs.

Value	Meaning
0	At the start of the hour (xx:00)
30	At half-past the hour (xx:30)
*/15	Every 15 minutes (00, 15, 30, 45)
0,30	At :00 and :30 each hour
1-5	At minutes 1, 2, 3, 4, and 5

Hour— range: 0–23

Which hour(s) of the day the job runs (24-hour clock, UTC by default).

Value	Meaning
0	Midnight (00:xx)
9	9 AM
*/6	Every 6 hours: midnight, 6am, noon, 6pm
9-17	Every hour from 9am through 5pm
0,12	Midnight and noon only

Day of Month— range: 1–31

Which day(s) of the month the job runs.

Value	Meaning
1	First day of every month
15	15th of every month
L	Last day of the month (not all cron variants)
1,15	1st and 15th of each month
*/5	Every 5th day: 1st, 6th, 11th, 16th, 21st, 26th, 31st

Month— range: 1–12

Which month(s) the job runs. Numeric or named (JAN–DEC).

Value	Meaning
1	January only
*/3	Every 3 months: Jan, Apr, Jul, Oct
6,12	June and December
1-3	January, February, March
JAN	January (named form — supported on most platforms)

Day of Week— range: 0–7 (0 and 7 = Sunday)

Which day(s) of the week the job runs. Both 0 and 7 represent Sunday.

Value	Meaning
0	Sunday
1	Monday
1-5	Monday through Friday (weekdays)
0,6	Saturday and Sunday (weekends)
MON	Monday (named form — supported on most platforms)

Special Characters

*Asterisk (wildcard)

Matches every value in the field's range.

* * * * *

Every minute of every hour, every day

,Comma (list)

Specifies a list of values.

0 9,17 * * *

At 9:00 AM and 5:00 PM every day

-Hyphen (range)

Specifies a range of values.

0 9-17 * * *

At the start of every hour from 9 AM to 5 PM

/Slash (step)

Specifies a step value. */n means 'every n units'. m/n means 'start at m, then every n'.

*/5 * * * *

Every 5 minutes (0, 5, 10, 15, … 55)

?Question mark (no-op)

Used in day-of-month or day-of-week to mean 'no specific value'. Useful when one of the two is already specified.

0 12 15 * ?

Noon on the 15th, any day of week (Quartz/Spring)

LL (last)

In day-of-month: last day of month. In day-of-week: last occurrence of that day in the month.

0 0 L * *

Midnight on the last day of every month (AWS EventBridge)

#Hash (nth weekday)

Specifies the nth occurrence of a weekday in the month.

0 9 * * 1#2

9 AM on the 2nd Monday of each month (Quartz/Spring)

WW (nearest weekday)

Nearest weekday (Mon–Fri) to the given day of the month.

0 9 15W * *

9 AM on the nearest weekday to the 15th (Quartz/Spring)

@ Shorthand Macros

Many cron implementations support @ macros as human-readable shortcuts. They are NOT universally supported — always verify your platform.

Macro	Equivalent	Meaning
@yearly / @annually	0 0 1 1 *	Once a year on Jan 1 at midnight
@monthly	0 0 1 * *	First day of every month at midnight
@weekly	0 0 * * 0	Every Sunday at midnight
@daily / @midnight	0 0 * * *	Every day at midnight
@hourly	0 * * * *	At the start of every hour
@reboot	(on startup)	Once at system startup (Linux crontab only)

Common Gotchas

Day of month AND day of week — it's an OR

If you specify both day-of-month and day-of-week (instead of *), most cron implementations run the job when EITHER condition is met, not both. So `0 0 1 * 1` runs at midnight on the 1st of the month AND every Monday.

Fix: To schedule on a specific weekday AND specific date, use application logic instead of cron.

The step value starts from the field's minimum, not zero

`*/5` in the minute field means 0, 5, 10, 15…55. But `1/5` means 1, 6, 11, 16…56. The start value matters.

Fix: Use `*/5` for clean intervals starting at 0, or `m/n` when you need a specific start offset.

Timezone: cron always runs in the server's local time

Standard crontab uses the system timezone. If your server is UTC, `0 9 * * *` fires at 09:00 UTC. Many cloud schedulers (GitHub Actions, AWS) always use UTC.

Fix: Always clarify which timezone you're scheduling in. Use `TZ=` prefix in modern crontabs or platform-specific timezone fields.

Month names and day names are not universally supported

`JAN` instead of `1`, or `MON` instead of `1` — most Linux cron implementations accept this, but Kubernetes CronJob, some cloud schedulers, and programming library parsers may not.

Fix: Use numeric values for maximum portability.

Day-of-week: 0 and 7 both mean Sunday

Standard cron supports both 0 and 7 for Sunday, which can cause confusion. Some implementations (Quartz) number weekdays 1-7 starting Monday.

Fix: Use 0 for Sunday consistently, and check your platform's documentation.

Quick Reference: Common Patterns

Expression	Meaning
* * * * *	Every minute
0 * * * *	Every hour (at :00)
0 0 * * *	Every day at midnight
0 9 * * 1-5	9 AM on weekdays
/15 * * *	Every 15 minutes
0 0 1 * *	Midnight on the 1st of each month
0 0 * * 0	Every Sunday at midnight
0 9,17 * * 1-5	9 AM and 5 PM on weekdays
30 8 1,15 * *	8:30 AM on the 1st and 15th
0 /6 * *	Every 6 hours

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