A cron job is a scheduled task on Unix-like systems managed by the cron daemon. It runs a command or script automatically at a defined time interval — for example, daily, hourly, or every 5 minutes. Each job is defined by a cron expression (5 or 6 space-separated fields) in a file called the crontab. Cron jobs are widely used for backups, log rotation, report generation, and any recurring automation task.

How do I generate a cron expression for every 5 minutes?

Use the step syntax: */5 * * * *. The */5 in the minute field means every 5th minute — at :00, :05, :10, :15 … :55. You can generate this automatically by selecting 'Every 5 min' from the Minute dropdown in this cron expression generator, or by clicking the 'Every 5 minutes' preset button.

What is the difference between AWS cron and Linux cron syntax?

AWS EventBridge cron uses 6 fields (adds a year field at the end) vs the standard 5-field Linux crontab format. AWS also requires a ? wildcard in either the day-of-month or day-of-week field — you cannot specify both. AWS weekdays are 1–7 (Sunday=1) while Linux uses 0–6 (Sunday=0). All AWS cron times run in UTC. Use the AWS CloudWatch tab in this generator to convert any Linux expression automatically.

How do I create a Kubernetes cron job schedule?

Kubernetes CronJobs use standard 5-field cron syntax in the spec.schedule field of a CronJob manifest. For example, schedule: '0 9 * * 1-5' runs a job at 9 AM on weekdays. Use the Kubernetes tab in this cron expression generator to get a ready-to-use CronJob YAML manifest with your schedule pre-filled.

What does */5 mean in a cron expression?

The */n syntax means every nth unit starting from the minimum value of that field. */5 in the minute field expands to 0,5,10,15,20,25,30,35,40,45,50,55 — running the job every 5 minutes. You can use step values in any field: */2 in the hour field means every 2 hours, and */15 in the minute field means every 15 minutes.

Cron Expression Generator

Q: How do I run a cron job every weekday at 9am?

Use the expression: 0 9 * * 1-5. The 0 in the minute field means at :00, 9 means 9 AM, and 1-5 in the day-of-week field means Monday through Friday. On AWS EventBridge the equivalent is cron(0 9 ? * MON-FRI *). Click the 'Weekdays 9–5' preset in this generator to start from a similar template, then adjust as needed.

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Free Cron Expression Generator

Generate, validate, and understand cron expressions with a visual editor. Supports Linux crontab, AWS CloudWatch, GitHub Actions, and Kubernetes formats.

Common Presets

cron-builder.sh

Visual Builder

Minute

Hour

Day

Month

Weekday

Expression

* * * * *

Next Run

—

Per Day

1,440

Plain English

Next 10 Runs

Field Reference

* Any / every value

*/n Every nth unit

a-b Range from a to b

a,b,c Specific values list

a-b/n Range with step

Field	Range
Minute	0–59
Hour	0–23
Day	1–31
Month	1–12
Weekday	0–7 (0,7=Sun)

What is a Cron Expression?

A cron expression is a string of five or six fields that defines a recurring schedule for automated tasks. Each field represents a unit of time: minute, hour, day of month, month, and day of week. Cron jobs run automatically on Linux servers, AWS EventBridge, GitHub Actions, and Kubernetes without any manual intervention.

Field	Position	Allowed Values	Example
Minute	1st	0–59	*/5 (every 5 minutes)
Hour	2nd	0–23	9 (9 AM)
Day of Month	3rd	1–31	1 (1st of month)
Month	4th	1–12	* (every month)
Day of Week	5th	0–7 (0 and 7 are Sunday)	1-5 (weekdays)

Cron Special Characters Explained

Cron expressions use five special characters to define complex schedules. Understanding these characters lets you build any recurring schedule without memorizing syntax.

Character	Name	Meaning	Example
*	Asterisk	Every value in field	* in hour means every hour
,	Comma	Multiple values	8,12,16 means 8AM, 12PM, 4PM
-	Hyphen	Range of values	1-5 means Monday to Friday
/	Slash	Step interval	*/15 means every 15 minutes
?	Question mark	No specific value (AWS/Kubernetes only)	Used when day-of-month or day-of-week is unspecified

Cron Shortcuts Reference

Most cron implementations support shortcut strings that replace the five-field expression with a readable keyword.

Shortcut	Equivalent	Description
@reboot	N/A	Run once at startup
@yearly	0 0 1 1 *	Once a year on January 1st
@monthly	0 0 1 * *	Once a month on the 1st
@weekly	0 0 * * 0	Once a week on Sunday
@daily	0 0 * * *	Once a day at midnight
@hourly	0 * * * *	Once an hour

AWS EventBridge Cron Syntax

AWS EventBridge uses a six-field cron expression wrapped in cron() syntax: cron(Minutes Hours Day-of-month Month Day-of-week Year). Unlike Linux cron, EventBridge requires a question mark (?) in either the Day-of-month or Day-of-week field when the other is specified.

Use Case	Expression
Every day at 10:15 AM UTC	cron(15 10 * * ? *)
Every weekday at 9 AM UTC	cron(0 9 ? * MON-FRI *)
First day of every month	cron(0 0 1 * ? *)
Every 5 minutes	cron(0/5 * * * ? *)

GitHub Actions Cron Syntax

GitHub Actions uses standard 5-field Unix cron syntax in the schedule trigger. All schedules run in UTC timezone. The minimum interval GitHub Actions supports is every 5 minutes.

on:
  schedule:
    - cron: '0 9 * * 1-5'  # Every weekday at 9 AM UTC

Cron Expression Examples

Use Case	Expression	Platform
Every minute	* * * * *	Linux
Every 5 minutes	/5 * * *	Linux
Every day at midnight	0 0 * * *	Linux
Every weekday at 9 AM	0 9 * * 1-5	Linux
First day of month	0 0 1 * *	Linux
Every Sunday at midnight	0 0 * * 0	Linux
Every 15 minutes	/15 * * *	Linux
Twice daily at 8AM and 8PM	0 8,20 * * *	Linux

Tip: click any expression to load it into the generator above.

Frequently Asked Questions

A cron job is a scheduled task on Unix/Linux systems that runs automatically at defined time intervals, managed by the cron daemon. It uses a 5-field cron expression to define when to run a command.

A cron job is a scheduled task on Unix-like systems managed by the cron daemon. It automatically runs a command or script at a defined time interval, such as hourly, daily, weekly, or any custom schedule. Each cron job is defined by a cron expression: 5 (or 6) space-separated fields representing minute, hour, day-of-month, month, and day-of-week. Jobs are stored in a file called the crontab (cron table). Common uses include database backups, log rotation, cache warming, and sending scheduled reports.

Use */5 * * * *. The */5 in the minute field means every 5th minute, running at :00, :05, :10 ... :55. Click the "Every 5 minutes" preset button above to generate it automatically.

Use the step syntax: */5 * * * *. The */5 in the minute field means "every 5th minute", running at :00, :05, :10, :15 ... :55. To generate this automatically, select Every 5 min from the Minute dropdown above, or click the Every 5 minutes preset button. The same step syntax works in any field: */2 means every 2 units, */15 means every 15 units.

AWS EventBridge cron uses 6 fields (adds a year field) vs 5-field Linux crontab, and requires ? in either day-of-month or day-of-week. All AWS schedules run in UTC; Linux crontab uses local system time.

Kubernetes CronJobs use standard 5-field cron syntax in the spec.schedule field. For example, schedule: "0 9 * * 1-5" runs a job at 9 AM on weekdays.

Kubernetes CronJobs use standard 5-field cron syntax in the spec.schedule field of a CronJob manifest. For example, schedule: "0 9 * * 1-5" runs a job at 9 AM on weekdays. Kubernetes also supports the shorthand aliases @hourly, @daily, @weekly, and @monthly. Use the Kubernetes tab in this cron job generator to get a complete, ready-to-apply CronJob YAML manifest with your schedule pre-filled.

*/5 means "every 5th unit from the minimum value." In the minute field it expands to 0, 5, 10, 15 ... 55, running the job every 5 minutes. The same step syntax works in any cron field.

The */n syntax means "every nth unit starting from the field minimum." The * expands to the full range and /n is the step interval. So */5 in the minute field expands to 0,5,10,15,20,25,30,35,40,45,50,55. You can also step over a range: 8-18/2 in the hour field means every 2 hours from 8 AM to 6 PM. This generator supports all step syntax in every field.

Use the expression 0 9 * * 1-5: 0 sets the minute to :00, 9 sets the hour to 9 AM, and 1-5 means Monday through Friday.

Use the expression 0 9 * * 1-5. The 0 sets the minute to :00, 9 sets the hour to 9 AM, and 1-5 in the day-of-week field means Monday through Friday. On AWS EventBridge the equivalent is cron(0 9 ? * MON-FRI *). Click the Weekdays 9–5 preset in this generator as a starting point, then adjust the hour dropdown to narrow it to exactly 9 AM.

What is a Cron Job?

A cron job is a scheduled task that runs automatically on a Unix-like server at a defined time or interval, managed by the cron daemon. The name comes from the Greek word chronos (time). Cron has been a core part of Linux and Unix system administration since the 1970s and remains the standard mechanism for task scheduling today.

Each cron job is defined by a cron expression: a compact string of 5 space-separated fields representing minute, hour, day-of-month, month, and day-of-week, paired with the command to execute. These entries are stored per-user in a file called the crontab (cron table), edited with crontab -e. The cron daemon wakes up every minute, reads the crontab, and runs any job whose schedule matches the current time. Common use cases include nightly database backups, hourly cache invalidation, weekly security scans, daily report emails, and continuous monitoring scripts.

How to Use This Cron Expression Generator

This free online cron generator works entirely in your browser — no sign-up, no install. There are three ways to build an expression:

1. Use a preset. Click any preset button at the top — "Every 5 minutes," "Daily at 9 AM," "Weekdays 9–5," and more. The expression field and all dropdowns update instantly.

2. Use the visual dropdowns. Select values for Minute, Hour, Day, Month, and Weekday from the dropdowns. The expression field updates in real time and the Plain English panel explains what the schedule means in plain language.

3. Type directly. Enter any cron expression, including step values (*/5), ranges (9-17), and comma lists (1,15), into the Expression field. The generator validates it instantly and syncs the dropdowns to match.

Cron Expression Examples for Linux, AWS and Kubernetes

The table below lists the most commonly needed cron job schedules with their Linux crontab expressions. Click any expression to load it directly into the generator above.

Expression	Schedule	AWS EventBridge
* * * * *	Every minute	cron(* * * * ? *)
/5 * * *	Every 5 minutes	cron(/5 * * ? *)
0 9 * * *	Daily at 9:00 AM	cron(0 9 * * ? *)
0 9 * * 1-5	Weekdays at 9:00 AM	cron(0 9 ? * MON-FRI *)
0 0 1 * *	1st of every month, midnight	cron(0 0 1 * ? *)
0 0 * * 0	Every Sunday at midnight	cron(0 0 ? * 1 *)
30 5 1,15 * *	5:30 AM on the 1st and 15th	cron(30 5 1,15 * ? *)
0 2 * * *	Nightly backup at 2:00 AM	cron(0 2 * * ? *)
0 /6 * *	Every 6 hours	cron(0 /6 * ? *)
0 0 1 1 *	Once a year — Jan 1 midnight	cron(0 0 1 1 ? *)

Tip: click any expression in the table to load it into the generator.

Cron Job Syntax Guide — All Fields Explained

A standard Linux cron job syntax has five fields in this order:

Position	Field	Allowed values	Special chars
1	Minute	0–59	* , - /
2	Hour	0–23	* , - /
3	Day of month	1–31	* , - / ?
4	Month	1–12 or JAN–DEC	* , -
5	Day of week	0–7 (0,7=Sun) or SUN–SAT	* , - /

The four special characters work in all fields: * means every value, , separates a list (e.g. 1,15), - defines a range (e.g. 9-17), and / sets a step interval (e.g. */5).

AWS Cron Expression Generator vs Linux Crontab

The AWS cron expression generator tab handles the most error-prone part of writing AWS EventBridge schedules: the format differences from standard Linux crontab.

Feature	Linux crontab	AWS EventBridge
Field count	5 fields	6 fields (adds year)
Format wrapper	0 9 * * 1-5	cron(0 9 ? * MON-FRI *)
Day/weekday conflict	OR logic — both can be set	Requires `?` in one field
Weekday numbering	0–6 (Sunday = 0)	1–7 (Sunday = 1)
Timezone	System local time	UTC only
Shorthand aliases	@daily, @hourly, @reboot	Not supported

The most common mistake when porting a Linux cron expression to AWS EventBridge is forgetting the ? wildcard. This generator's AWS CloudWatch tab performs the conversion automatically and shows the complete cron() string ready to paste into an EventBridge rule.