Question 1

What is a cron expression?

Accepted Answer

A cron expression is a string of five fields — minute, hour, day of month, month, and day of week — that tells a scheduler (cron) when to run a job. For example, "0 9 * * 1-5" means "at 09:00, Monday through Friday".

Question 2

What do the five fields mean?

Accepted Answer

Reading left to right: minute (0–59), hour (0–23), day of month (1–31), month (1–12 or JAN–DEC), and day of week (0–6 or SUN–SAT, where both 0 and 7 mean Sunday). An asterisk (*) in a field means "every value".

Question 3

What does */5 mean in a cron expression?

Accepted Answer

The slash is the step operator. "*/5" in the minute field means "every 5th minute" — i.e. 0, 5, 10, 15 … 55. You can combine it with ranges too: "0-30/10" means every 10 minutes from minute 0 to 30.

Question 4

How are the next run times calculated?

Accepted Answer

This tool evaluates your expression against the calendar minute by minute (in UTC) and lists the next few matching times. The preview is illustrative — your server may run in a different timezone, so always confirm against your scheduler's configured zone.

Question 5

Does the day-of-month and day-of-week use AND or OR?

Accepted Answer

Standard Unix cron uses OR when both day-of-month and day-of-week are restricted: the job runs if either matches. If only one of the two is set (the other is *), only that one has to match. This tool follows the same rule.

Question 6

Is my data sent anywhere?

Accepted Answer

No. The parser, the natural-language explanation and the next-run preview all run entirely in your browser. Nothing about your expressions is uploaded or stored on a server.

Cron Expression Generator

What does `0 0 * * *` mean?

Related cron expressions

Frequently Asked Questions

Cron Expression Generator

Cron Expression Generator

What does 0 0 * * * mean?

Related cron expressions

Frequently Asked Questions

Cron Expression Generator

What does `0 0 * * *` mean?