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Cron Parser

Parse and understand cron expressions. Get human-readable descriptions, next execution times, and build expressions from presets.

Minute

Hour

Day (Month)

Month

Day (Week)

Common Presets

Next 10 Run Times

Timezone:

Field Reference

*Any value (wildcard)

,Value list separator (1,3,5)

-Range of values (1-5)

/Step values (*/5)

LLast day of month (dom only)

?No specific value (dom/dow)

Understanding Cron Expressions

Cron Field Positions

The cron daemon, originally from UNIX, uses a simple 5-field scheduling syntax defined in POSIX 1003.2. 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 both 0 and 7 represent Sunday). The scheduler checks all running jobs every minute and executes those whose fields match the current time.

Cron Expression Examples

Expression	Description
0 0 * * *	Run at midnight every day
/10 * * *	Run every 10 minutes
0 9-17 * * 1-5	Run hourly during business hours (Mon–Fri)
0 0 15,30 * *	Run at midnight on the 15th and 30th of each month
30 4 1 * *	Run at 4:30 AM on the 1st of every month
0 0 * * 1	Run at midnight every Monday
@reboot	Run at system startup (not supported everywhere)
@daily	Equivalent to 0 0 * * *
@weekly	Equivalent to 0 0 * * 0
@monthly	Equivalent to 0 0 1 * *

Frequently Asked Questions

What are the five fields in a cron expression?

In order: minute (0-59), hour (0-23), day of month (1-31), month (1-12), and day of week (0-6, where 0 is Sunday). Each field can use a specific value, a range, a step (*/5), or a wildcard (*) to mean "every."

What does /15 * * * mean?

This runs every 15 minutes, every hour, every day — the */15 in the minute field means "every 15th minute" (0, 15, 30, 45).

Why does my cron job run at the wrong time?

The most common cause is a timezone mismatch — most cron daemons run in the server's system timezone (often UTC), not your local timezone, so a job scheduled for "9am" needs to account for that offset.

Can I schedule a job for a specific day of the week and month combined?

Cron treats day-of-month and day-of-week as an OR condition when both are restricted (not wildcards) — meaning the job runs when either condition is true, which can be a common source of confusion.