Cron Expression Explainer

Cron Expression Format

A standard cron expression has 5 space-separated fields: minute hour day-of-month month day-of-week. Each field controls when the job fires.

Special Characters

• * matches every value in the field's range.
• , separates a list: 1,3,5 means 1st, 3rd, and 5th.
• - defines an inclusive range: 1-5 means 1 through 5.
• / defines a step: */15 means every 15 units; 10/5 means every 5 units starting at 10.

Language Descriptions

Descriptions are generated with cronstrue, an open-source library that translates cron expressions into human-readable text in 33 locales, including Arabic, Chinese (Simplified and Traditional), Japanese, Korean, Russian, and many European languages.

Next Run Calculation

Run times are computed entirely in your browser. The engine advances from the current local time, minute by minute, testing each candidate against all five fields. When day-of-month and day-of-week are both restricted, either condition can trigger the job (the traditional UNIX union rule). Your browser's local timezone is used automatically.

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