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Cron Expression Explainer

Parse any cron schedule and see next run times — or build one visually. All client-side.

What is a cron expression?

A cron expression is a compact string that defines a recurring schedule for automated tasks. The name comes from the Unix cron daemon, which reads a crontab (cron table) file and runs commands at the times each expression specifies.

A standard cron expression has five space-separated fields: minute, hour, day-of-month, month, and day-of-week. Each field accepts a number, a wildcard *, a range, a list, or a step value.

Cron is used in Linux/macOS system administration, CI/CD pipelines, cloud schedulers (AWS EventBridge, GCP Cloud Scheduler, GitHub Actions), and application-level job queues (Sidekiq, Celery, node-cron, and many others).

Cron field reference

Field Range Special chars Example
Minute 0 – 59 * , - / */15 — every 15 minutes
Hour 0 – 23 * , - / 9-17 — 9 AM through 5 PM
Day of month 1 – 31 * , - / 1,15 — 1st and 15th
Month 1 – 12 * , - / 1-6 — January through June
Day of week 0 – 6 (Sun=0) * , - / 1-5 — Monday through Friday

Special characters: * matches every value in the field. , separates a list of values (e.g. 1,3,5). - defines an inclusive range (e.g. 9-17). / defines a step — */5 means every 5 units, 10/5 means every 5 units starting at 10.

Common cron patterns

Pattern Description
* * * * * Every minute
0 * * * * Every hour, on the hour
0 9 * * 1-5 9:00 AM on weekdays (Mon – Fri)
0 0 * * * Midnight every day
0 0 1 * * Midnight on the 1st of every month
*/15 * * * * Every 15 minutes
0 */6 * * * Every 6 hours (00:00, 06:00, 12:00, 18:00)
30 8 * * 1 8:30 AM every Monday
0 0 1 1 * Midnight on January 1st (yearly)
0 12 * * 0 Noon every Sunday

Many schedulers also support convenient aliases: @hourly (every hour), @daily or @midnight (once a day at midnight), @weekly (Sunday midnight), @monthly (1st of the month at midnight), and @yearly or @annually (January 1st at midnight). This explainer supports all of these aliases.

Cron & Scheduling Guides