Cron Expression Generator and Explainer
Type or pick a five-field cron expression and read what it does in plain English, with each field broken down and the next ten run times listed in UTC or your own time zone. Errors say exactly which field is wrong. Everything runs in your browser.
Every 15 minutes, between 09:00 and 17:59, on Monday through Friday
- Minute
- */15
- 0, 15, 30, 45
- Hour
- 9-17
- 9, 10, 11, 12, 13, 14, 15, 16, 17
- Day of month
- *
- every value
- Month
- *
- every value
- Day of week
- 1-5
- Mon, Tue, Wed, Thu, Fri
Calculating…
Cron uses the time zone of the machine it runs on, often UTC on servers. Times that a clock change skips are left out of the local list.
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Developer & WebAbout the Cron Expression Generator and Explainer
A standard cron expression has five fields: minute (0 to 59), hour (0 to 23), day of month (1 to 31), month (1 to 12 or JAN to DEC) and day of week (0 to 7 or SUN to SAT, where both 0 and 7 are Sunday). A star means every value, a comma makes a list, a hyphen makes an inclusive range, and a slash adds a step, so */15 is every 15 minutes and 1-10/3 is 1, 4, 7 and 10. The shortcuts @yearly, @monthly, @weekly, @daily, @midnight and @hourly are also understood. One rule catches many people out. When both day fields are restricted, which means neither starts with a star, cron runs the job on a day that matches either one, so 0 0 13 * 5 runs on the 13th and on every Friday, not only on Friday the 13th. When one of the day fields starts with a star, both must match. This tool applies that rule, as cronie does, and points it out when it matters. It reads standard five-field cron only. Quartz and Spring expressions with a seconds field, a year, or the characters ?, L, W and # are different and are rejected with an explanation. The next-run list is calculated for the time zone you choose and never looks further than eight years, so a date such as 30 February returns nothing. Cron uses the time zone of the machine it runs on, which is often UTC, so check yours. In a local zone, times skipped by a clock change are left out, and how a scheduler treats them can vary.
What does */5 * * * * mean?▾
It runs every 5 minutes, at minutes 0, 5, 10 and so on up to 55, every hour of every day. The star in the minute field with a /5 step means every fifth minute.
Why does my cron job run on days I did not expect?▾
When both the day-of-month and day-of-week fields are restricted, cron runs on a day that matches either one. So 0 0 13 * 5 runs on the 13th and on every Friday. Use a script check if you need both.
Does cron support a seconds field?▾
Standard cron does not. It has five fields and its finest unit is a minute. A sixth field for seconds appears in Quartz and Spring, which use different syntax from this tool.
Which time zone does cron use?▾
The time zone of the machine or service that runs it, which is often UTC on servers. This tool lists run times in UTC or in your browser's zone so you can compare them with your own clock.