Cron expression explainer

Type a 5-field cron expression to see what it means in plain English and exactly when it will run next.

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Cron expression (minute hour day-of-month month day-of-week)

Next 5 runs (your time zone: )

Cron syntax

┌───────── minute (0-59)
│ ┌─────── hour (0-23)
│ │ ┌───── day of month (1-31)
│ │ │ ┌─── month (1-12 or JAN-DEC)
│ │ │ │ ┌─ day of week (0-7 or SUN-SAT; 0 and 7 are Sunday)
* * * * *  command

Syntax	Meaning	Example
`*`	every value	`* * * * *` every minute
`a,b,c`	list	`0 8,12,18 * * *` at 08:00, 12:00 and 18:00
`a-b`	range (inclusive)	`0 9 * * 1-5` 09:00 on weekdays
`*/n`	every n-th value	`/10 * * *` every 10 minutes
`a-b/n`	every n-th value in a range	`0 8-18/2 * * *` every 2 hours from 08:00 to 18:00
`@hourly`	`0 * * * *`
`@daily` / `@midnight`	`0 0 * * *`
`@weekly`	`0 0 * * 0`
`@monthly`	`0 0 1 * *`
`@yearly` / `@annually`	`0 0 1 1 *`
`@reboot`	once at startup

The day-of-month / day-of-week trap

If both day fields are restricted, cron runs when either matches. 0 0 13 * 5 runs on every 13th and every Friday, not only on Friday the 13th. If one of the two fields starts with *, both must match. The explainer and next-run list above follow this rule.

Why a cron job doesn't run

Different environment. Cron runs with a minimal PATH (usually /usr/bin:/bin), no shell profile and no virtualenv. Use absolute paths to every program, or you get command not found.
Script not executable or has Windows line endings: see permission denied and bad interpreter.
Time zone. Cron uses the server's time zone (check timedatectl), not yours.
% in the command is turned into a newline by cron; escape it as \%.
No output. Append >> /tmp/job.log 2>&1 to capture errors, and check grep CRON /var/log/syslog or journalctl -u cron.

Six-field expressions with seconds (Quartz, Spring @Scheduled) are a different dialect and are not standard crontab syntax.

Last updated 2026-11-01.