What does */5 * * * * mean?

It runs every five minutes: at minutes 0, 5, 10 and so on of every hour, every day.

How do I run a job every weekday at 9 am?

Use 0 9 * * 1-5, which means minute 0, hour 9, any day of the month, any month, Monday to Friday.

Why does my job run on more days than expected?

When both day-of-month and day-of-week are set, standard cron runs on days that match either field.

Does cron use my local time?

It uses the time zone of the server or scheduler. Many servers use UTC, so check before you rely on a local hour.

Are six-field expressions with seconds supported?

No. This tool covers the standard five-field format.

Cron Expression Generator & Explainer

Edit the five fields or click a preset. You get the finished expression, a plain-English description and the next five times it will run.

What cron expressions are

Cron is the classic Unix scheduler. A cron expression tells it when to run a job using five space-separated fields: minute, hour, day of the month, month and day of the week. A star means "every value". So 0 9 * * 1-5 reads as minute 0 of hour 9 on every day of the month, every month, from Monday to Friday: 9:00 on weekdays. The same format is used by many tools beyond the system crontab, including CI services, Kubernetes CronJobs and cloud schedulers, though some of them add extra fields or have small differences.

The syntax you can use

A number such as 5 picks one value.
A list such as 1,15 picks several: the 1st and 15th.
A range such as 9-17 covers every value from 9 to 17 inclusive.
A step such as */15 or 10-50/10 means every 15th value, or every tenth value within a range.
Names such as JAN to DEC and SUN to SAT work in the month and weekday fields. In the weekday field, both 0 and 7 mean Sunday.

The day-of-month and weekday trap

In standard cron, if both the day-of-month and the day-of-week fields are restricted (not a star), the job runs when either matches, not when both do. So 0 0 13 * 5 runs on the 13th of every month and also on every Friday. Many people expect only Friday the 13th. This tool follows the standard behaviour when it calculates the next run times, so you can see what will really happen.

Time zones and daylight saving

Cron runs in the time zone of the machine or service that hosts it, and that is often UTC on servers. A job scheduled for 02:30 may be skipped or run twice when clocks change in regions with daylight saving. For critical jobs, schedule in UTC. The next-run preview can be shown either in your own local time or in UTC with the checkbox.

Limits

This generator uses the five-field format. It does not support special strings like @daily, six-field formats with seconds (used by Quartz and Spring) or extensions such as L and #. The preview looks up to a year and a half ahead, so a very rare schedule might show fewer than five times. Everything runs in your browser.