How cron schedule syntax works

Cron syntax is used to describe when a scheduled task should run. You may see cron fields in places such as Ptero schedules, cPanel cron jobs, and other hosting control panels.

Cron fields

A cron schedule is usually split into five fields:

1. Minute controls the minute of the hour. For example, 0 runs at the start of the hour.
2. Hour controls the hour of the day, using 24-hour time. For example, 3 means 3 AM.
3. Day of Month controls the day number in the month. For example, 1 means the first day of the month.
4. Month controls which month the task runs in. For example, 1 means January.
5. Day of Week controls which weekday the task runs on. Depending on the system, Sunday may be 0 or 7.

Common values

The * symbol means every possible value for that field. You can also use numbers, ranges, lists, and step values. A step value uses / to say how often something should repeat inside that field.

1. * means every value.
2. 0 means that exact value.
3. 1,3,5 means a list of values.
4. 1-5 means a range of values.
5. */5 means every 5 in that field. For example, in the Minute field it means every 5 minutes. In the Hour field it means every 5 hours.

Examples

0 * * * *     Runs every hour
0 3 * * *     Runs every day at 3 AM
*/30 * * * *  Runs every 30 minutes
0 0 * * 1     Runs every Monday at midnight
0 0 1 * *     Runs on the first day of every month

If your control panel offers preset schedule options, use those unless you specifically need custom timing.