Cron Parser
Parse and explain cron schedule expressions in plain English.
What is a cron expression?
Cron is a time-based job scheduler in Unix-like operating systems. A cron expression is a string of five (or six, with seconds) fields that define when a scheduled task should run. The name comes from Chronos, the Greek god of time. Cron expressions are used in Linux crontabs, CI/CD pipelines (GitHub Actions, Jenkins), cloud functions (AWS Lambda, Google Cloud Scheduler), and application schedulers (Node.js node-cron, Python APScheduler).
Cron expression structure
┌───── minute (0–59)
│ ┌───── hour (0–23)
│ │ ┌───── day of month (1–31)
│ │ │ ┌───── month (1–12 or JAN–DEC)
│ │ │ │ ┌───── day of week (0–7, both 0 and 7 = Sunday, or SUN–SAT)
│ │ │ │ │
* * * * *
Special characters:
* = every / any value
, = list of values (e.g. 1,3,5)
- = range (e.g. 1-5)
/ = step values (e.g. */15 = every 15)
? = no specific value (day of month OR day of week, not both)Common cron expression examples
| Expression | Meaning |
|---|---|
| * * * * * | Every minute |
| 0 * * * * | Every hour (at minute 0) |
| 0 9 * * * | Every day at 9:00 AM |
| 0 9 * * 1-5 | Weekdays at 9:00 AM (Mon–Fri) |
| 0 9 * * 1 | Every Monday at 9:00 AM |
| 0 0 1 * * | First day of every month at midnight |
| 0 0 1 1 * | January 1st at midnight (annual) |
| */15 * * * * | Every 15 minutes |
| 0 */6 * * * | Every 6 hours |
| 0 8-18 * * 1-5 | Every hour from 8 AM to 6 PM, weekdays |
| 30 4 1,15 * 0 | At 4:30 AM on the 1st and 15th, and Sundays |
| @daily | Shorthand for 0 0 * * * (midnight) |
| @weekly | Shorthand for 0 0 * * 0 (Sunday midnight) |
| @monthly | Shorthand for 0 0 1 * * (first of month) |
Timezone gotchas with cron
Cron jobs run in the system timezone of the server unless explicitly configured otherwise. A cron job set to run at "9:00 AM" on a UTC server will fire at 9:00 AM UTC — which may be a different local time in your region. Always verify whether your cron scheduler uses UTC or a local timezone, and use an explicit timezone setting if available (e.g. in GitHub Actions or AWS EventBridge).
Frequently asked questions
What is a cron expression?
A cron expression is a string of five (or six) fields that defines a recurring schedule — minute, hour, day of month, month and day of week — used by Unix cron and many schedulers to run tasks automatically.
What does the asterisk (*) mean?
An asterisk means "every" value for that field. For example, * in the minute field means every minute, and 0 * * * * means at minute 0 of every hour.
How do I run a job every 15 minutes?
Use */15 * * * *. The */15 means "every 15th minute", so the job runs at :00, :15, :30 and :45 of every hour.
What is the difference between 5-field and 6-field cron?
Standard cron uses 5 fields. Some systems (like Quartz and some Linux variants) add a leading seconds field, making 6 fields. This parser explains each field so you can tell which format you are using.
Format: minute hour day-of-month month day-of-week Special characters: * = any value , = list (1,3,5) - = range (1-5) / = step (*/15)