Cron Expression Parser

Explain a cron expression in words and list its next run times.

About Cron Expression Parser

A cron expression parser explains a crontab schedule in plain English and lists its next five run times, with each of the five fields decoded as you type.

How to use

  1. Paste a 5-field expression such as */15 9-17 * * 1-5, or click an example. Macros like @daily and @hourly are expanded.
  2. Read the description, the per-field breakdown and the next five runs. Switch the run times between UTC and your own time zone.
  3. If a field is wrong the error names it, for example an hour of 24 or a backwards range.

What it does

  • Reads the standard five fields: minute, hour, day-of-month, month and day-of-week, in that order. Each accepts *, single values, ranges (1-5), steps (*/15, 1-5/2) and comma lists.
  • Accepts three-letter month and weekday names (JAN, MON) in any case; weekday 7 means Sunday, like 0.
  • Follows cron's day rule: when both day-of-month and day-of-week are set, the job runs when either one matches, and the page says so.
  • Walks forward from now to find the next five instants, and reports when a schedule can never run, such as the 31st of a 30-day month.
  • Does not read six-field (seconds) or seven-field (year) formats used by Quartz and some cloud schedulers.

Example

30 9 * * 1-5
→ At 09:30 on Monday through Friday.

*/15 9-17 * * *
→ Every 15 minutes, between 09:00 and 17:59.

Privacy

The expression is parsed in the browser. No request is made, and nothing is stored.

Frequently asked questions

What do the 5 fields in a cron expression mean?
From left to right: minute (0-59), hour (0-23), day of month (1-31), month (1-12 or JAN-DEC) and day of week (0-7 or SUN-SAT, where 0 and 7 are both Sunday). A star in a field means every value.
What does */15 mean in cron?
Every 15th value of that field, counting from the start. In the minute field it means at :00, :15, :30 and :45 of each hour. 1-30/5 limits the step to a range: 1, 6, 11, up to 26.
What time zone does cron use?
The system time zone of the machine running the cron daemon, which on most servers is UTC. Some systems let you set CRON_TZ at the top of the crontab. This page shows next runs in UTC or in your browser zone so you can compare.
What happens when both day of month and day of week are set?
In standard cron the job runs when either field matches, not both. 0 0 13 * 5 runs on the 13th of every month and on every Friday, not only on Friday the 13th.