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
- Select the frequency — Choose how often the job should run — every minute, hourly, daily, weekly, monthly, or custom.
- Configure the schedule — Set the specific minute, hour, day of month, month, and day of week for your cron job.
- Read the expression — The tool displays the 5-field cron expression with a human-readable description of when it will run.
- View the next run times — Check the next 5 scheduled execution times to verify the expression does what you expect.
- Copy the expression — Grab the cron expression for your crontab, CI/CD pipeline, or scheduled task configuration.
Tips and Best Practices
- → Know the five fields. Left to right: minute (0–59), hour (0–23), day of month (1–31), month (1–12), day of week (0–7, where 0 and 7 are Sunday).
- → Use * for 'every' and */n for intervals.
*/5 * * * *means every 5 minutes.0 */2 * * *means every 2 hours on the hour. - → Be careful with day-of-month and day-of-week. When both are set (not *), most cron implementations run the job when EITHER condition is true — not when both are true. This catches many beginners off guard.
- → Avoid scheduling at midnight. Many cron jobs are scheduled at 0 0 * * * (midnight). Spread your jobs across different times to avoid resource contention on servers.
Frequently Asked Questions
Built by Derek Giordano · Part of Ultimate Design Tools