What is a Cron Expression and How Does It Work?
A cron expression is a string format used in Unix-like operating systems and distributed task schedulers to configure recurring automated jobs. The standard specification consists of five fields separated by spaces: Minute (0-59), Hour (0-23), Day of Month (1-31), Month (1-12 or JAN-DEC), and Day of Week (0-6 or SUN-SAT).
Because deciphering complex cron strings with step values (/), ranges (-), and wildcards (*) can be challenging, a cron parser translates cryptic expressions into natural human language and calculates exact future execution timestamps so you can deploy scheduled jobs with confidence.
How to Use This Cron Parser (3-Step Quick Guide)
Enter Cron Expression or Preset
Type a 5-field cron string or click any quick preset like 'Every 5 minutes' or 'Every Monday at 9am'.
Read Human-Readable Translation
View the instant plain-English translation and the breakdown of each individual time field.
Inspect Upcoming Execution Schedule
Review next upcoming run timestamps to verify exact schedule execution before deploying.
Cron Expression 5-Field Syntax
Standard 5-field format used in crontab files and Kubernetes CronJobs.
| Field | Name | Allowed Values | Special Characters | Example Expression |
|---|---|---|---|---|
| 1 | Minute | 0-59 | * , - / | */15 (every 15 minutes) |
| 2 | Hour | 0-23 | * , - / | 0,12 (midnight and noon) |
| 3 | Day of Month | 1-31 | * , - / | 1,15 (1st and 15th) |
| 4 | Month | 1-12 or JAN-DEC | * , - / | * (every month) |
| 5 | Day of Week | 0-6 (0=Sun) | * , - / | 1-5 (Monday to Friday) |
Frequently Asked Questions
What do the five asterisks (* * * * *) in cron mean?
Five asterisks represent standard cron's maximum frequency: the job executes every minute of every hour of every day.
How do I schedule a job to run every 15 minutes?
Use `*/15 * * * *` to run the command every 15 minutes starting at minute 0 (at :00, :15, :30, :45).
Does standard cron support seconds or years?
Standard Linux cron uses 5 fields (minutes to day-of-week). Extended schedulers (like Quartz or Spring) add optional seconds or year fields.
What timezone do cron jobs run in?
System cron jobs run in the host server's local timezone unless specified otherwise via the `CRON_TZ` or `TZ` environment variable in the crontab.