Cron Expression Parser - Validate Schedules

Parse single cron expressions into human-readable descriptions with next run times. Supports 5-field syntax, special strings (@daily), ranges, step values.

Common Crontab Examples

Expression	Description	Action
`0 * * * *`	Every hour (at minute 0)
`/5 * * *`	Every 5 minutes
`0 9 * * 1-5`	Weekdays at 9:00 AM
`0 0 1 * *`	First day of every month at midnight
`30 2 * * 0`	Every Sunday at 2:30 AM
`0 0 * * *`	Daily at midnight
`@daily`	Special string: daily at midnight
`@hourly`	Special string: every hour
`0 0 1 1 *`	January 1st at midnight (yearly)
`15,45 * * * *`	At minutes 15 and 45 of every hour

Crontab Syntax Reference

Field Format

* * * * *
│ │ │ │ │
│ │ │ │ └─ Day of week (0-7, where 0 and 7 are Sunday)
│ │ │ └─── Month (1-12)
│ │ └───── Day of month (1-31)
│ └─────── Hour (0-23)
└───────── Minute (0-59)

Special Characters

* - Any value (wildcard)
, - List separator (e.g., 1,3,5)
- - Range (e.g., 1-5)
/ - Step values (e.g., */15 for every 15 units)

Special Strings

@yearly or @annually - Run once a year (0 0 1 1 *)
@monthly - Run once a month (0 0 1 * *)
@weekly - Run once a week (0 0 * * 0)
@daily or @midnight - Run once a day (0 0 * * *)
@hourly - Run once an hour (0 * * * *)
@reboot - Run at startup

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Frequently Asked Questions

A crontab expression is a time-based scheduling format used in Unix-like systems to define when a job should run. It consists of 5 fields (minute, hour, day of month, month, day of week) that specify the schedule using numbers, ranges, lists, and step values.

A standard cron expression has 5 fields separated by spaces: minute (0-59), hour (0-23), day of month (1-31), month (1-12), and day of week (0-7, where both 0 and 7 represent Sunday). Each field can use wildcards (*), ranges (1-5), lists (1,3,5), or step values (*/15).

Common special strings include @yearly or @annually (0 0 1 1 *), @monthly (0 0 1 * *), @weekly (0 0 * * 0), @daily or @midnight (0 0 * * *), @hourly (0 * * * *), and @reboot (runs once at startup). These provide convenient shortcuts for common schedules.

Step values use the syntax */n to specify intervals. For example, */15 in the minute field means every 15 minutes, */2 in the hour field means every 2 hours, and 0-30/5 means every 5 minutes between 0 and 30. They provide a compact way to define regular intervals.

Ranges use a hyphen to specify a continuous interval, like 1-5 for Monday through Friday in the day of week field, or 9-17 for 9 AM to 5 PM in the hour field. You can combine ranges with step values (1-5/2) or use multiple ranges in a comma-separated list (1-5,10-15).

The tool parses each field of the cron expression and generates a natural language description. For example, '0 9 * * 1-5' becomes 'At 09:00, Monday through Friday'. It handles wildcards, ranges, lists, and step values to create clear, understandable schedules.

Yes, the tool calculates the next scheduled run times based on the current date and time. It shows multiple upcoming executions so you can verify your cron schedule is correct. This is especially useful for complex expressions with specific day or month requirements.

Yes, the tool validates cron expressions against standard syntax rules. It checks field ranges (0-59 for minutes, 0-23 for hours, etc.), validates step values, and ensures proper formatting. Invalid expressions show clear error messages explaining what's wrong.

Common expressions include: '0 * * * *' (every hour), '*/5 * * * *' (every 5 minutes), '0 0 * * *' (daily at midnight), '0 9 * * 1-5' (weekdays at 9 AM), '0 0 1 * *' (first day of month), and '30 2 * * 0' (Sundays at 2:30 AM).

Cron expressions are evaluated in the timezone of the system running the cron daemon. This tool calculates next run times using your browser's local timezone. When deploying cron jobs to servers, ensure the server timezone matches your expectations or use UTC for consistency.