What is a cron expression?

A cron expression is a string format used to schedule tasks in Unix/Linux systems. It specifies when to run commands: minute, hour, day of month, month, and day of week. Example: 0 9 * * 1-5 means 9 AM on weekdays.

What does the asterisk (*) mean in cron?

An asterisk (*) means 'every' in that field. So * in the hour field means every hour. You can use ranges (1-5), lists (1,3,5), and intervals (*/15) for more specific scheduling.

How do I run something every 15 minutes?

Use */15 in the minute field: */15 * * * *. This tells cron to run at 0, 15, 30, and 45 minutes of every hour, every day.

Cron Expression Generator

Build valid cron expressions using a user-friendly interface. Select minute, hour, day, month, and weekday.

Minute

Hour

Day

Month

Weekday

Cron Expression

* * * * *

Next 5 Runs:

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Cron Format

Format: minute hour day month weekday

Examples:

0 9 * * 1-5 — Every weekday at 9 AM
*/15 * * * * — Every 15 minutes
0 0 1 * * — First day of every month
0 12 * * 0 — Every Sunday at noon

Special: * means any, - means range, , means list, / means step

How to Use

Select fields – Adjust minute, hour, day, month, weekday fields
See expression – Cron format updates in real-time
View next runs – See when your cron will execute
Copy expression – Copy the cron to your clipboard

Common Cron Patterns

0 9 * * 1-5 – Every weekday at 9 AM
*/15 * * * * – Every 15 minutes
0 0 1 * * – First day of each month
0 12 * * 0 – Every Sunday at noon
0 0 * * * – Every day at midnight

Related Tools

Unix Time Now – Get current timestamp
Unix Time to Human – Convert timestamps
Unix Time Diff – Calculate time differences