Cron Expression Explainer
Paste a cron expression below to validate it and get a plain-English description of when it runs. Standard five-field cron syntax is supported, including steps (*/2), ranges (1-5), and lists (1,3,5).
Valid cron expression
Invalid cron expression
Field breakdown
| Field | Value | Meaning |
|---|
Next 5 run times (approximate, based on local time)
Cron Syntax Reference
A standard cron expression has five fields separated by spaces:
| Position | Field | Allowed values | Special characters |
|---|---|---|---|
| 1 | Minute | 0–59 |
* , - /
|
| 2 | Hour | 0–23 |
* , - /
|
| 3 | Day of month | 1–31 |
* , - /
|
| 4 | Month | 1–12 |
* , - /
|
| 5 | Day of week | 0–7 (0 and 7 = Sunday) |
* , - /
|
Special Characters
| Character | Meaning | Example | Result |
|---|---|---|---|
*
|
Any / every value |
* * * * *
|
Every minute |
*/n
|
Every nth value (step) |
*/15 * * * *
|
Every 15 minutes |
n-m
|
Range from n to m |
0 9-17 * * *
|
At minute 0, every hour from 9 AM to 5 PM |
n,m
|
List of specific values |
0 8 * * 1,3,5
|
At 8 AM on Monday, Wednesday, Friday |
n-m/s
|
Step within a range |
0 8-18/2 * * *
|
Every 2 hours from 8 AM to 6 PM |
Common Examples
| Expression | Meaning |
|---|---|
| * * * * * | Every minute |
| 0 * * * * | Every hour (at minute 0) |
| */5 * * * * | Every 5 minutes |
| 0 0 * * * | Daily at midnight |
| 0 9 * * 1-5 | Weekdays at 9 AM |
| 0 0 1 * * | First day of every month at midnight |
| 0 0 * * 0 | Every Sunday at midnight |
| 0 0 1 1 * | Once a year — January 1st at midnight |
Frequently Asked Questions
What is a cron job?
A cron job is a scheduled task managed by the cron daemon on Unix-like operating systems (Linux, macOS). It runs commands or scripts automatically at fixed times, dates, or intervals — useful for backups, log rotation, sending emails, syncing data, and much more. Configuration is stored in a file called a crontab (cron table). If you need to build a cron expression from scratch, try the Crontab Builder.
Does 0 and 7 both mean Sunday for day-of-week?
Yes. Most cron implementations treat both 0 and 7 as Sunday in the day-of-week field. Monday is 1, Tuesday 2, and so on through Saturday as 6.
Why isn't my cron running at the right time?
The most common cause is a timezone mismatch. Cron runs in the system timezone of the server, which may differ from your local time. Check timedatectl or /etc/timezone on your server to confirm.
What is the difference between cron and crontab?
cron is the background service (daemon) that actually runs jobs. A crontab is the text file that lists the scheduled tasks. You edit your personal crontab with crontab -e and view it with crontab -l.
Does this tool support @reboot, @daily, and other shortcuts?
Not currently — this validator handles the standard five-field syntax. Common shortcuts and what they map to: @hourly = 0 * * * *, @daily = 0 0 * * *, @weekly = 0 0 * * 0, @monthly = 0 0 1 * *, @yearly = 0 0 1 1 *.
