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Cron Expression Tester & Schedule Explainer

Free online cron expression generator, tester, and translator. Convert cryptic 5-field cron strings into plain English schedules for crontab and automation.

Enter standard 5-part crontab syntax (Minute, Hour, Day of Month, Month, Day of Week).

Preset Schedules:
Human Translation

Runs every 15 minutes, at hour 0, at day of months (1,15), every month, on from weekday 1 through 5.

Field Parsing Breakdown
Minute (0–59)*/15every 15 minutes
Hour (0–23)0at hour 0
Day of Month (1–31)1,15at day of months (1,15)
Month (1–12)*every month
Day of Week (0–6)1-5from day of week 1 through 5

What is a Cron Job?

In Unix-like computer operating systems, cron is a background time-based job scheduler (daemon). Systems engineers, DevOps architects, and software developers configure cron jobs to automate periodic routines—such as database backups, log rotations, SSL certificate renewals, cache warmers, and automated maintenance scripts.

The configuration file containing instructions for the cron daemon is known as a crontab (cron table).

Anatomy of a 5-Field Standard Cron Expression

A standard POSIX cron expression is comprised of 5 space-delimited fields:

 ┌───────────── Minute (0 - 59)
 │ ┌─────────── Hour (0 - 23, 24-hour clock)
 │ │ ┌───────── Day of the Month (1 - 31)
 │ │ │ ┌─────── Month of the Year (1 - 12)
 │ │ │ │ ┌───── Day of the Week (0 - 6, where 0 = Sunday)
 │ │ │ │ │
 * * * * *

Supported Special Characters:

  • * (Asterisk / Wildcard): Matches every possible value of the field (e.g., every minute or every hour).
  • , (Comma / Value List): Specifies a list of discrete trigger values (e.g., 1,15,30).
  • - (Hyphen / Range): Specifies an inclusive continuous range (e.g., 1-5 for Monday through Friday).
  • / (Slash / Step Intervals): Specifies rate increments (e.g., */10 in the minute field runs every 10 minutes).

Common Crontab Recipes & Examples

ExpressionSchedule MeaningStandard Use Case
*/5 * * * *Every 5 minutesHealth checks & API heartbeats
0 * * * *Every hour at minute 0Hourly analytics rollups
0 0 * * *Once a day at midnight (00:00)Nightly database dumps & backups
0 2 * * 0Every Sunday at 2:00 AMHeavy weekly disk defrag & cleanup
0 9 * * 1-5Monday through Friday at 9:00 AMBusiness hours digest notifications
0 0 1 * *Midnight on the 1st of every monthMonthly billing & invoicing generation

How to Install a Cron Job in Linux / macOS

To install or edit scheduled jobs on your server:

  1. Open your terminal shell and open your user’s crontab: 
    crontab -e
  2. Add your schedule and executable command line on a new line: 
    0 3 * * * /usr/bin/python3 /opt/scripts/backup.py >> /var/log/backup.log 2>&1
  3. Save and close the editor. The cron daemon reads changes automatically without requiring a service reboot.
  4. To verify all currently active scheduled routines: 
    crontab -l