What Is a Cron Expression?

Cron expressions define recurring schedules using a compact five-field syntax: minute, hour, day-of-month, month, and day-of-week. They power scheduled tasks in Unix/Linux systems, CI/CD pipelines (GitHub Actions, GitLab CI), cloud services (AWS CloudWatch, Google Cloud Scheduler), and job queues. This builder lets you construct cron expressions visually and see the next execution times.

Cron Syntax Quick Reference

* = every value. */n = every n units. n-m = range from n to m. n,m = specific values n and m. Fields in order: minute (0-59), hour (0-23), day (1-31), month (1-12), weekday (0-6, where 0 = Sunday).

How to Use This Cron Builder

  1. Select the frequency — Choose how often the job should run — every minute, hourly, daily, weekly, monthly, or custom.
  2. Configure the schedule — Set the specific minute, hour, day of month, month, and day of week for your cron job.
  3. Read the expression — The tool displays the 5-field cron expression with a human-readable description of when it will run.
  4. View the next run times — Check the next 5 scheduled execution times to verify the expression does what you expect.
  5. Copy the expression — Grab the cron expression for your crontab, CI/CD pipeline, or scheduled task configuration.

Tips and Best Practices

Frequently Asked Questions

What is a cron expression?
A five-field string defining a schedule: minute, hour, day of month, month, day of week. Example: '0 9 * * 1' = 9 AM every Monday. Used in Unix, CI/CD, and cloud schedulers.
What does * mean in cron?
Asterisk means 'every' or 'any value.' */5 means every 5 units, 1-5 means range 1 through 5.
How do I run a job daily?
'0 0 * * *' runs at midnight daily. '0 9 * * *' runs at 9 AM daily. First field = minute, second = hour, asterisks = every day/month/weekday.
What is a cron expression?+
A cron expression is a string of five fields separated by spaces that defines a recurring schedule. The fields represent minute, hour, day of month, month, and day of week. Cron is used by Unix/Linux systems, CI/CD platforms (GitHub Actions, GitLab CI), cloud schedulers (AWS CloudWatch, Google Cloud Scheduler), and task automation tools.
What does the cron expression '0 9 * * 1-5' mean?+
It means 'at 9:00 AM, Monday through Friday.' Breaking it down: 0 (minute 0), 9 (9th hour / 9 AM), * (every day of the month), * (every month), 1-5 (Monday through Friday). This is a common schedule for business-hours tasks.
How do I test a cron expression?+
Use a cron expression tool like this one to see the next scheduled run times. You can also test in a terminal with crontab -e to add a temporary job that writes to a log file, then watch the log to verify timing.

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Related Article How to Build Cron Expressions for Scheduled Tasks →

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