Next 5 run times
Enter an expression and click Explain.
About Cron Expressions
A standard cron expression consists of five fields: minute (0–59), hour (0–23), day of month (1–31), month (1–12), and day of week (0–7, where 0 and 7 both represent Sunday). Each field supports wildcards (*), ranges (1-5), lists (1,3,5), and step values (*/10). While this syntax is powerful and concise, it can be error-prone to write and difficult to verify by inspection. This tool bridges that gap by parsing the expression, explaining what each field means in plain English, and computing upcoming execution times using your local timezone. It helps you verify schedules before deploying them to production, reducing the risk of jobs running at the wrong time.
How to Use Cron Explainer
- Enter a 5-field cron expression (e.g.,
0 9 * * 1-5for "every weekday at 9:00 AM"). - Click Explain to see a plain-English description of the schedule.
- Review the Next 5 run times to verify the expression fires when you expect.
- Adjust the expression and re-explain until the schedule is correct.
Key Features
- Translates cron expressions into plain English descriptions
- Shows the next 5 scheduled run times in your local timezone
- Supports wildcards (*), ranges, lists, and step values
- Validates expression syntax and highlights errors
- 100% browser-based — no data sent to any server
- Use alongside the Cron Generator to build expressions visually
When to Use This Tool
- Verifying a cron schedule before deploying it to production or CI/CD
- Understanding an existing crontab entry inherited from another team
- Debugging scheduled jobs that run at unexpected times
- Learning cron syntax as a reference alongside documentation
- Testing different schedule patterns without modifying a live system
Technical Details
The tool parses each of the five fields according to the POSIX cron specification. Wildcards (*) match all valid values for the field. Ranges (e.g., 1-5) expand to all values in the range. Lists (e.g., 1,15) match specific values. Step values (e.g., */5) generate every Nth value starting from the field's minimum. The next-run calculation iterates forward from the current time, checking each minute against the parsed expression until 5 matches are found (limited to approximately one year ahead for performance). Times are displayed in your browser's local timezone using JavaScript's Intl.DateTimeFormat.
Conclusion
The Cron Explainer is an essential tool for anyone working with scheduled tasks. It converts complex cron syntax into clear English descriptions and verifies timing with upcoming run dates — all privately in your browser, with no risk to your production systems.