Cron Syntax Explained: 5 Fields and Symbols (Free Tool)

Cron syntax is five fields separated by spaces: minute, hour, day of month, month and day of week. Each field holds a number, a * for "every", or a pattern built from , - and /. So 30 18 * * 5 means 18:30 every Friday. Some schedulers add a seconds field or symbols like L and #, the usual source of confusion. Paste any expression into the free cron expression generator to have it explained in plain English with its next run times.

Cron syntax: the five fields

┌──────── 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; 7 is also Sunday)
│ │ │ │ │
* * * * *  command to run

Hours use the 24-hour clock, so 6 pm is 18. Months and weekdays accept three-letter English names in most cron versions: 0 9 * * MON-FRI is the same as 0 9 * * 1-5.

The four special characters

Character	Meaning	Example	Reads as
*	Every value	* * * * *	Every minute
,	A list	15,45 * * * *	At :15 and :45 every hour
-	A range	0 9-17 * * *	On the hour, 09:00 to 17:00
/	A step	*/15 * * * *	Every 15 minutes

You can combine them. 0 9-17/2 * * 1-5 runs at 9, 11, 13, 15 and 17 on weekdays. 0,30 8-10 * * * runs at 8:00, 8:30, 9:00, 9:30, 10:00 and 10:30.

A step counts from the start of its range and restarts each hour, day or month. So */7 in the minute field gives :00, :07 ... :56 and then :00 again, with a 4-minute gap. Our guide on running cron every 5 minutes shows why steps that divide 60 evenly behave best.

The day-of-month OR day-of-week rule

This one surprises almost everyone. When both day fields are restricted (neither is *), standard cron runs the job when either matches:

0 0 13 * 5

You might read that as "Friday the 13th". Cron reads it as "the 13th of every month, and every Friday". The generator spells it out: "At 00:00, on day 13 of the month, and on Friday". If only one day field is restricted, only that one counts, which is what you'd expect.

To get "Friday the 13th", schedule it on Fridays (0 0 * * 5) and have your script check the date.

Shortcuts: @daily and friends

Many cron versions accept these in place of the five fields:

Shortcut	Same as
@hourly	0 * * * *
@daily or @midnight	0 0 * * *
@weekly	0 0 * * 0
@monthly	0 0 1 * *
@yearly or @annually	0 0 1 1 *

@reboot (run once at start-up) also exists in many Linux crons, but it isn't a schedule, so the generator doesn't accept it.

Extensions: L, W, # and ?

Some schedulers go beyond the standard. The best known is Quartz, used in many Java applications, and its syntax shows up in other tools too. As per the Quartz documentation:

• Seconds come first, and there's an optional year at the end, so expressions have 6 or 7 fields: 0 0/5 * * * ? is "every 5 minutes".
• Day of week runs 1-7, with 1 = Sunday, not 0-6. 2 is Monday in Quartz but Tuesday in standard cron.
• ? means "no specific value" and goes in one of the two day fields, because Quartz doesn't allow both to be set.
• L means "last": L in day of month is the last day of the month; 6L in day of week is the last Friday.
• W means the nearest weekday to a date: 15W is the weekday closest to the 15th.
• # means "the nth": 6#3 is the third Friday of the month.

The EveryApp generator uses the standard five-field format, so it tells you when you've pasted something else. It accepts ? as a synonym for *, but L, W and # give an error such as "The day of month field "L" has a value outside 1-31.", and a seconds field gives "That has six fields... drop the seconds field."

Platform differences to watch

• Linux cron (crontab): the five-field standard described here, in the server's local time zone.
• GitHub Actions: standard five fields. As per GitHub's documentation (2026), schedules run in UTC unless you set a time zone, the shortest interval is every 5 minutes, and runs can be delayed at busy times such as the start of each hour.
• Quartz and Spring: six or seven fields with seconds first, plus L, W, # and ?. Check the docs for your framework, as Spring's own format differs from Quartz in places.
• Cloud schedulers: many use either the standard format or a Quartz-like one, often with their own time zone setting. Always check which your platform expects; pasting a five-field expression into a six-field scheduler shifts every field by one.

The time zone point is the biggest source of "my job ran at the wrong time". Tick Show in UTC (most servers) in the generator to see run times as a UTC server would, or use the time zone converter for a specific city.

Reading an expression, step by step

Take 30 2 * * 1-5:

1. Minute 30, hour 2: at 02:30.
2. Day of month *, month *: any date.
3. Day of week 1-5: Monday to Friday.

So: 02:30 every weekday. Practising like this gets fast; if you validate cron strings in code, the regex tester is handy for checking a pattern against a list of examples, though a real cron parser is the safer check.

Try your expression

Paste any five-field expression, read the plain-English version and the next eight runs, then copy it. The free cron expression generator works in your browser and needs no account.