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Decode Cron Schedules
Cron Expression Parser
Convert cryptic Unix cron expressions to clear, human-readable descriptions and compute upcoming run times in your timezone.
5 fields: minute hour day-of-month month day-of-week
Cheatsheet
Fields
minute:0–59
hour:0–23
dom:1–31
month:1–12
dow:0–6
Syntax
* = All values
1-5 = Range
*/15 = Every 15th
1,3,5 = List
Names
MonthsJAN, FEB, MAR, APR, MAY, JUN, JUL, AUG, SEP, OCT, NOV, DEC
DaysSUN, MON, TUE, WED, THU, FRI, SAT
Understanding Cron Expressions
Understanding Fields
A cron expression has 5 fields: minute (0–59), hour (0–23), day-of-month (1–31), month (1–12), day-of-week (0–6). Each field defines when the job runs.
Wildcards & Ranges
The * (wildcard) means "any value". Ranges (1-5) mean 1,2,3,4,5, and steps (*/15) mean every 15th value (e.g., 0,15,30,45 for minutes).
Common Patterns
Weekdays at 9 AM is 0 9 * * MON-FRI, first of month is 0 0 1 * *, and hourly is 0 * * * *.
Timezone Awareness
This tool calculates upcoming run times in your selected timezone, and daylight saving time (DST) transitions are handled automatically.
FAQ
What happens when both day-of-month and day-of-week are specified?
According to standard cron semantics, if both are specified, OR logic applies: the job runs on the specified day-of-month OR the specified day-of-week. E.g., 0 9 15 * MON runs on the 15th of any month OR any Monday at 9 AM.
Why is day-of-week 0–6, with 0 = Sunday?
This is the standard POSIX cron convention: 0 = Sunday, 1 = Monday, …, 6 = Saturday. Some systems allow 7 for Sunday; this tool converts 7 to 0.
What happens with impossible dates like February 29 or April 31?
February 29 exists only in leap years, so a job on Feb 29 runs only in leap years. April 31 doesn't exist, so a job on that date is skipped.
What happens during daylight saving time (DST) transitions?
During spring DST transition, skipped times are skipped. During fall transition, times that occur twice may run twice. This tool uses your browser's timezone database to handle DST automatically.