Cron Explainer
Cron expression explainer online. Convert cron to plain English with field breakdown. Understand any cron schedule—explain cron expressions free.
📖
Explain Cron Expression
Paste expression to understand
This cron expression means:
At 09:00 AM, Monday through Friday
Field Breakdown
Minute 0
Hour 9
Day *
Month *
Day 1-5
Minute
0 0 Hour
9 9 Day of Month
* every day of month Month
* every month Day of Week
1-5 1 through 5* any value
, value list
- range
/ step
Features
- Instantly convert complex cron expressions into human-readable English text
- Detailed breakdown of each individual field (Minute, Hour, Day, etc.)
- Automatically flags syntax or boundary errors
- Supports standard 5-part and prolonged 6-part Quartz expressions
- Recognizes day and month abbreviations (e.g., MON, DEC)
Common Use Cases
- Decoding inherited legacy cron configurations from an old codebase
- Verifying that a scheduled job runs exactly when you intend before deploying
- Teaching junior developers how to read server job configurations
- Documenting existing scheduled operations for system infrastructure reports
Translating Cron to English
A Cron Explainer reverse-engineers a raw cron string back into human terms by analyzing the relationships between its temporal fields.
For example, the expression 30 4 * * 1-5 evaluates each component left-to-right:
- 30: At minute 30
- 4: Past hour 4 (4:30 AM)
- *: Every day of the month
- *: Every month
- 1-5: Only on Monday through Friday
Result: "At 04:30 AM, Monday through Friday."
Examples
Valid - Complex Offset
15,45 8-18 * * * Valid - Last Day Logic
0 12 L * * Invalid - Invalid Syntax Warning
65 * * * *Frequently Asked Questions
What does the asterisk `*` mean?
The asterisk acts as a wildcard meaning "every". If placed in the hour field (`0 * * * *`), the job runs every hour at minute zero.
Why does my string say invalid?
Strings can fail validation if a number exceeds the temporal bounds (like minute 61) or if there are an incorrect number of spaces (for instance, 4 fields instead of 5).
Can I translate Quartz and AWS CloudWatch schedules?
Yes! The explainer dynamically detects if a 6th field is provided (seconds or year) and parses it using Quartz/AWS specific constraints.
💡 Tips
- Use the explainer output as a comment directly above your cron job configuration in your code to help future developers.
- Watch out for `Day of Month` vs `Day of Week` conflicts. Often, setting both to restricted values can act as an `OR` union depending on the daemon.