Cron Expression Builder

Understanding Cron Syntax

Cron expressions are standard scheduling strings used by servers, databases, and continuous integration systems to trigger jobs. While incredibly compact, they can be difficult to read.

A standard expression uses five fields separated by spaces:

1. Minute (0–59)
2. Hour (0–23)
3. Day of the month (1–31)
4. Month (1–12)
5. Day of the week (0–6, where 0 is Sunday)

This builder reads the expression live and translates it into a human-readable summary.

Supported Special Characters

Standard cron syntax uses a few special characters to define complex schedules without writing out every exact value:

• Asterisk *: Matches any value. An asterisk in the hour field means “every hour.”
• Comma ,: Defines a list of specific values. 1,15,30 in the minute field triggers at those exact minutes.
• Dash -: Defines a range. 1-5 in the weekday field triggers Monday through Friday.
• Slash /: Defines a step interval. */10 in the minute field triggers every 10 minutes.

Local Timezone Execution

Because servers often run in UTC, calculating when a job will actually trigger in your local timezone can lead to off-by-one errors. The execution preview calculates the next 10 triggers and formats them perfectly into your browser’s local time, making it easy to confirm that your midnight database backup won’t accidentally run in the middle of the afternoon.