What is a cron expression?
Cron is a Unix job scheduler that runs commands on a fixed schedule. A cron expression is a 5-field pattern (minute hour day-of-month month day-of-week) that defines when a job runs. For example, 0 9 * * 1-5 means 'at 9:00 AM Monday through Friday'. Fields accept specific values, ranges (1-5), step values (*/15), and lists (1,3,5). Cron is used to schedule database backups, report generation, cache purges, and any recurring server task.
How to use this tool
- 1 Type a cron expression in the input field — or click one of the quick preset buttons.
- 2 The field breakdown shows exactly what each of the five positions means.
- 3 The description below translates the expression into plain English.
- 4 The Next 10 runs table shows exact timestamps — toggle UTC to see them in UTC instead of local time.
Frequently asked questions
What order are the five fields in?
Minute (0-59), Hour (0-23), Day of month (1-31), Month (1-12), Day of week (0-6, where 0=Sunday). A common mistake is putting month before day-of-month — cron uses the opposite order to most date formats.
What does */ mean in a field?
*/n means "every n units". */15 in the minute field means "every 15 minutes" (at :00, :15, :30, :45). */2 in the hour field means "every 2 hours".
Can I have both day-of-month and day-of-week set?
Yes, but the behavior varies by implementation. Traditional cron uses OR — the job runs if either condition matches. Some modern schedulers use AND. This tool previews next runs using OR semantics.
Does cron support seconds?
Standard 5-field cron does not — the smallest unit is one minute. Some systems (Quartz Scheduler, AWS EventBridge) add a 6th second field or a 7th year field. This tool supports only standard 5-field cron.
Is anything sent to a server?
No. Expression parsing and next-run calculation run entirely in your browser.