Cron Expression Explainer: plain English, field breakdown and next run times

Examples

Field by field

    Next 10 runs

      About Cron Expression Explainer

      This tool turns a cron expression into plain English. Paste a five-field schedule, a six-field one with seconds first, or a macro such as @daily, and it explains what it does, field by field, and lists the next 10 times it will run.

      It understands lists, ranges, steps and month and weekday names, and applies the standard rule that day of month and day of week match as an OR when both are set. Mistakes are reported against the field they are in, such as 60 in the minute field.

      Everything runs in your browser. Nothing you type is uploaded.

      How to use it

      1. Type or paste a cron expression, or click an example.
      2. Read the sentence at the top and the breakdown of each field.
      3. Fix any field marked in red; the message says what is allowed.
      4. Choose Local or UTC to see the next 10 run times in that time zone.

      Frequently asked questions

      What is a cron expression?

      A cron expression is a short schedule written as five space-separated fields: minute, hour, day of month, month and day of week. For example, 30 8 * * 1 means 08:30 every Monday. Each field can hold a number, a list (1,15), a range (1-5), a step (*/10) or a name such as JAN or MON.

      Does it support seconds and macros like @daily?

      Yes. A sixth field in front is read as seconds, the form used by Quartz, Spring and node-cron. The macros @yearly, @annually, @monthly, @weekly, @daily, @midnight and @hourly are expanded to their five-field form, and @reboot is explained as a run at system start.

      What happens when both day of month and day of week are set?

      Standard cron runs the job when either field matches, not both. So 0 0 13 * FRI runs on every 13th and on every Friday. If one of the two fields starts with an asterisk, such as *, the other one alone decides. This tool follows that rule and says so when it applies.

      Why does the tool show an error for L, W, # or a year field?

      Those are extensions from Quartz and similar schedulers, such as L for the last day or 5#2 for the second Friday. Standard Linux cron does not understand them, so the tool flags them instead of guessing. Seven-field expressions with a year are not supported either.

      Which time zone are the next run times in?

      You choose: your device's local time zone or UTC. The times come from your browser's Intl support, including daylight saving changes. Wall-clock times that do not exist because the clocks jump forward are left out. Your server may run in a different zone, so check what your scheduler uses.

      Is my cron expression sent anywhere?

      No. Parsing, explaining and calculating run times all happen in your browser, and nothing is uploaded. The expression is only added to the page address so you can share or bookmark it.