Cron Expression Explainer
Understand any cron expression in plain English — with next run times
How to Use the Cron Expression Explainer
- Enter a cron expression (5 fields: minute hour day month weekday).
- Click Explain to see a plain-English breakdown and the next 5 scheduled run times.
Supports *, */N, ranges (1-5), and lists (1,3,5).
What is Cron Expression Explaining?
The Cron Expression Explainer translates complex 5-part and 6-part cron schedule expressions (such as `*/15 * * * *` or `0 2 * * 1-5`) into clear, human-readable English descriptions. It details the minute, hour, day of month, month, and day of week intervals, calculating upcoming execution timestamps to help developers verify automated task schedules.
Common Uses
- Verifying scheduled server cron jobs and Kubernetes CronJobs before deploying
- Auditing scheduled tasks in cloud serverless platforms (AWS EventBridge, GitHub Actions)
- Debugging timing misconfigurations in automated database backup routines
- Learning cron syntax conventions and special characters (`*`, `/`, `-`, `,`, `L`, `W`)
Frequently Asked Questions
What do the 5 fields of a standard cron expression represent?
From left to right: Minute (0-59), Hour (0-23), Day of the month (1-31), Month (1-12 or JAN-DEC), and Day of the week (0-7, where both 0 and 7 represent Sunday).
What is the difference between 5-field and 6-field cron expressions?
Standard UNIX cron uses 5 fields. Some systems (like Quartz, Spring Framework, or AWS) use a 6-field format that adds a 'Seconds' field at the beginning or a 'Year' field at the end.
What does */10 mean in a cron field?
The slash operator indicates step values. In the minute field, `*/10` means 'every 10 minutes starting from minute 0'.
Notes from this implementation
Say the schedule in a sentence
The explainer takes an expression and writes the schedule it describes, field by field. It is the check on the generator. Paste */15 * * * * and you should read “every 15 minutes,” not “at minute 15.” The star is every value. The slash is a step. A range is inclusive.
If the sentence mentions a sixth field you did not type, you are in the wrong dialect. The page documents the five-field reading this project uses. It does not execute the job, and it does not know your server’s time zone. “09:00” is 09:00 in the zone of the scheduler, which is often UTC on a container host.