What do the five cron fields mean?

In order they are minute (0-59), hour (0-23), day-of-month (1-31), month (1-12), and day-of-week (0-6, where 0 and 7 are both Sunday). A sixth leading field, when present, is seconds.

What do the special characters do?

An asterisk means every value. A dash defines a range like 1-5. A comma builds a list like 1,15. A slash sets a step, so */15 means every 15 units starting from the field minimum.

How are day-of-month and day-of-week combined?

Standard cron treats them as an OR when both are restricted: the job runs when either the day-of-month or the day-of-week matches. This tool lists each constraint it found so you can spot that case.

Can it read month and weekday names?

Yes. Names such as JAN, DEC, MON, and FRI are accepted and converted to their numeric equivalents before the schedule is described.

Does it support the 6 field seconds form?

Yes. If you provide six fields the first is treated as seconds (0-59), matching Quartz and many modern schedulers. Five fields use the classic Unix crontab layout.

Cron Expression to Human Text

Reading a cron expression

A cron expression is a compact way to describe a repeating schedule, but the five or six space-separated fields are easy to misread. This tool parses the expression the same way a scheduler does and tells you, in plain English, exactly when the job will fire. Paste something like 0 9 * * 1-5 and it reads back “at 09:00, on Monday, Tuesday, Wednesday, Thursday and Friday”.

How it works

Each field is expanded into the concrete set of values it matches. The parser handles four operators per field: * for every value, a range such as 1-5, a comma list such as 1,15,30, and a step such as */15 or 10-50/5. Month and weekday names like JAN or MON are mapped to numbers first, and 7 in the weekday field is normalised to 0 so Sunday is recognised either way.

Once every field is a set of numbers, the tool decides how to phrase it. If minutes and hours both match everything it says “every minute”; if only the minute is fixed it says “at minute N of every hour”; otherwise it lists the specific clock times. It then appends any day-of-week, day-of-month, and month restrictions it found.

*/15 9-17 * * 1-5   ->   every 15 minutes during 09:00-17:00 on weekdays
0 0 1 1 *           ->   at 00:00 on day-of-month 1 in January

Tips and notes

When both the day-of-month and day-of-week fields are restricted, classic cron runs the job if either one matches, not both. The tool lists each restriction separately so you can catch an unintended OR. If you need a seconds-resolution schedule, supply six fields and the leading field is interpreted as seconds, the convention used by Quartz and similar schedulers.