What does an asterisk mean in a cron expression?

An asterisk means “every possible value” for that field — for example, an asterisk in the hour field means the job can trigger during any hour.

What happens if both day-of-month and day-of-week are set to specific values?

Most cron implementations treat this as an OR condition, running the job when either field's condition is satisfied, not only when both match simultaneously — a common source of confusion.

How do I schedule a job to run every 15 minutes?

Use a step value in the minute field: */15 * * * * triggers the job at minute 0, 15, 30, and 45 of every hour.

Cron Expression Helper

Build cron expressions visually, get human-readable explanations, and preview the next run times.

Cron Expression (5 fields: minute hour day month weekday)

Every minute

Presets

Visual Builder

Next 5 Run Times

How to Use

Type a cron expression directly in the input field for an instant human-readable explanation.
Use the Visual Builder to set each field using every/specific/range/step modes — the expression updates automatically.
Click any Preset to load a common schedule instantly.
The Next 5 Run Times panel shows when the job will next fire based on your current local time.
Click Copy to copy the expression to your clipboard.

Field Reference

Field	Position	Allowed Values	Special Chars
Minute	1st	0–59	* , - /
Hour	2nd	0–23	* , - /
Day of Month	3rd	1–31	* , - /
Month	4th	1–12	* , - /
Day of Week	5th	0–7 (0&7=Sun)	* , - /

About this Cron Expression Helper

Cron is the standard scheduling syntax used by Unix/Linux systems and countless automation tools to run tasks at fixed intervals, but its five-field shorthand format is genuinely hard to read at a glance without practice.

The five fields

minute hour day-of-month month day-of-week

Each field accepts a specific number, a range (1-5), a list (1,3,5), a step value (*/15 for every 15 units), or an asterisk meaning "every possible value." All five fields must be satisfied for the schedule to trigger.

Common examples

0 9 * * * — every day at 9:00 AM
*/15 * * * * — every 15 minutes
0 0 1 * * — midnight on the first day of every month
0 17 * * 5 — every Friday at 5:00 PM

The day-of-month and day-of-week interaction

If both the day-of-month and day-of-week fields are set to specific values (not *), most cron implementations treat them as an OR condition — the job runs when either condition matches, not only when both do. This is one of the most common sources of unexpected cron behavior.