Cron Job Generator

Cron syntax is five fields of terse numbers and asterisks that decide when a scheduled job runs, and misreading it has consequences that only appear later. The classic mistake is a schedule intended to run at nine each morning that instead runs sixty times an hour, discovered when the mailbox fills or the bill arrives.

This tool translates a cron expression into plain English so you can confirm it means what you think before it goes live. The fields cover minute, hour, day of month, month and day of week, and each accepts ranges, lists and step values, which is where readability breaks down fastest.

Two details cause most confusion. Cron runs in the server's time zone, not yours, so a job set for a convenient hour locally may fire in the middle of a busy period on the server, and daylight saving changes can make a job run twice or not at all. Second, specifying both a day of month and a day of week makes the job run when either matches, not both.

How to use the Cron Job Generator

1. Enter or paste the cron expression you want to understand.
2. Read the plain English description generated below it.
3. Adjust the fields until the description matches your intent exactly.
4. Consider the server time zone before finalising the hour.
5. Copy the expression into your crontab, CI configuration or scheduler.

Examples

• An administrator confirms that a backup expression really means 02:30 every night rather than every half hour.
• A developer checks a CI schedule intended to run on weekdays only before committing it.
• A team validates a monthly report job that must fire on the first day of each month.

Frequently asked questions

What do the five fields mean?

In order: minute, hour, day of month, month, and day of week. An asterisk means every value for that field.

What does */15 do?

It is a step value. In the minute field it means every fifteenth minute, so the job runs four times an hour.

Which time zone does cron use?

The server's configured time zone. Set the server to UTC where possible to avoid daylight saving surprises.

Why did my job run on an unexpected day?

When both day of month and day of week are specified, most cron implementations run the job if either field matches.

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