Cron Expression Builder
Build and decode cron expressions visually with human-readable descriptions — 100% local
About Cron Builder
Cron expressions schedule recurring jobs on Unix-like systems, CI services, and many job schedulers. A standard expression has five fields: minute, hour, day of month, month, and day of week. Symbols such as * (any), / (step), - (range), and , (list) combine to describe schedules like "every 15 minutes on weekdays".
This builder lets you write or edit an expression and shows a plain-language explanation together with the next scheduled run times, so you can confirm it does what you intended before deploying it. Scheduler implementations differ in details such as time zone and seconds fields, so check your platform's documentation.
Common use cases
- Checking when a copied expression will actually run next.
- Building a schedule such as every weekday at 09:30 without memorizing the syntax.
- Explaining an unfamiliar expression found in a config or crontab.
- Catching mistakes such as confusing day of month with day of week.
Frequently asked questions
- Why does my job run at a different hour than expected?
- Most schedulers evaluate cron in the server's time zone, often UTC. Convert your local time before choosing the hour.
- Does this support six-field expressions with seconds?
- The tool works with the standard five-field format. Some platforms such as Quartz add a seconds field, so adapt accordingly.
- What does */5 mean?
- It means every five units of that field, for example every five minutes when used in the minute field.