Cron Expression Explainer

Paste a 5-field cron expression and get a plain-English explanation of when it runs, with support for ranges, lists, and step values.

The five cron fields

Position	Field	Allowed values
1	Minute	0–59
2	Hour	0–23
3	Day of month	1–31
4	Month	1–12
5	Day of week	0–6 (0 = Sunday)

Special characters: * means every value, , separates a list, - sets a range, and / sets a step — */15 in the minute field means every 15 minutes.

Common cron examples

Expression	Runs
* * * * *	Every minute
*/5 * * * *	Every 5 minutes
0 * * * *	At the start of every hour
0 0 * * *	Every day at midnight
30 2 * * *	Every day at 2:30 AM
0 9 * * 1-5	9:00 AM, Monday to Friday
0 0 * * 0	Every Sunday at midnight
0 0 1 * *	Midnight on the first day of every month
0 */6 * * *	Every 6 hours

Things that catch people out

• Time zone: cron runs in the server's time zone, which is often UTC rather than your local time.
• Day of month and day of week together: if both are set (not *), most cron versions run the job when either matches, not only when both do.
• Overlapping runs: if a job takes longer than its interval, a second copy can start before the first finishes.
• Output: cron runs without your usual terminal setup, so use full paths to programs and save the output to a log file to see errors.

Frequently asked questions

What format does this expect?

Standard 5-field cron syntax: minute, hour, day of month, month, and day of week — e.g. "0 9 * * 1-5" for 9 AM on weekdays.

Does it support ranges, lists, and steps?

Yes — ranges like "1-5", lists like "1,3,5", and step values like "*/15" (every 15 units) are all supported.

How do I run a job every 15 minutes?

Use */15 * * * * — it runs at :00, :15, :30 and :45 past every hour.

Is 0 or 7 Sunday?

In standard cron, 0 is Sunday, and many versions also accept 7 as Sunday. Using 0 works everywhere.