A cron expression is a string of 5 fields separated by spaces that defines a schedule for automated tasks (cron jobs) on Unix/Linux systems. Each field represents a unit of time: minute (0-59), hour (0-23), day of month (1-31), month (1-12), and day of week (0-7, where 0 and 7 = Sunday). Cron expressions are widely used in server administration, CI/CD pipelines, and cloud scheduling services.

Field	Position	Range	Description
Minute	1st	0-59	Minute of the hour when the job runs
Hour	2nd	0-23	Hour of the day (0 = midnight, 23 = 11 PM)
Day of Month	3rd	1-31	Day of the month
Month	4th	1-12	Month (1 = January, 12 = December)
Day of Week	5th	0-7	Day of the week (0 & 7 = Sunday, 1 = Monday, ..., 6 = Saturday)

• * (asterisk) — Matches every possible value. * * * * * means every minute.
• / (slash) — Step value. */5 * * * * means every 5 minutes.
• , (comma) — List separator. 0 9,17 * * * means at 9 AM and 5 PM.
• - (hyphen) — Range. 0 9-17 * * * means every hour from 9 AM to 5 PM.
• ? (question mark) — No specific value (used in some cron implementations like Quartz).
• L, W, # — Advanced modifiers in Quartz cron (e.g., last day, nearest weekday, nth occurrence).

Use the expression */5 * * * *. This means: every 5 minutes (*/5 in the minute field), every hour, every day, every month, every day of the week. The */5 syntax divides the minute range (0-59) into steps of 5, matching minutes 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, and 55.

Use 1-5 in the day-of-week field. For example, 0 9 * * 1-5 runs at 9:00 AM every Monday through Friday. The values are: 0=Sunday, 1=Monday, 2=Tuesday, 3=Wednesday, 4=Thursday, 5=Friday, 6=Saturday. You can also use names like MON-FRI in some cron implementations.

Some cron implementations support shorthand special strings:

• @yearly or @annually = 0 0 1 1 * (January 1st at midnight)
• @monthly = 0 0 1 * * (1st of every month at midnight)
• @weekly = 0 0 * * 0 (Every Sunday at midnight)
• @daily or @midnight = 0 0 * * * (Every day at midnight)
• @hourly = 0 * * * * (Every hour at minute 0)
• @reboot = Runs at system startup (no time schedule)

In standard Unix cron, if both the day-of-month and day-of-week fields are non-* values, the job runs when either condition is met (OR logic). For example, 0 0 1 * 0 runs at midnight on the 1st of every month AND every Sunday. This can be surprising — if you want both conditions to apply (AND logic), you may need to use a wrapper script or a different scheduler.

Yes! Many cron implementations support 3-letter abbreviations. For months: jan, feb, mar, apr, may, jun, jul, aug, sep, oct, nov, dec. For days: sun, mon, tue, wed, thu, fri, sat. Example: 0 0 * * mon-fri runs at midnight on weekdays. Note that not all systems support names, so numeric is more portable.

Use this translator tool to see the human-readable meaning and preview upcoming execution times. You can also validate cron expressions by checking that: (1) there are exactly 5 space-separated fields, (2) each field uses valid numbers/ranges within the allowed range, (3) special characters are used correctly, and (4) the schedule makes logical sense. For mission-critical cron jobs, always test in a staging environment first.

Standard Unix cron uses 5 fields. Quartz Scheduler (popular in Java applications) uses 6 or 7 fields, adding seconds (and optionally years). Quartz also supports additional special characters like ? (no specific value), L (last), W (nearest weekday), and # (nth occurrence). If you're using Quartz, your expression might look like 0 0/5 9-17 ? * MON-FRI (every 5 minutes, 9 AM–5 PM, weekdays). This translator focuses on standard 5-field cron but can help understand the core concepts.