What is a cron expression?

A cron expression is a string of five space-separated fields that define when a recurring task should run: minute (0–59), hour (0–23), day-of-month (1–31), month (1–12), and day-of-week (0–6, where 0 is Sunday). For example, '0 9 * * 1' means 'at 9:00 AM every Monday'.

What does */n mean in a cron field?

The slash (/) is the step operator. '*/n' means 'every n units starting from the minimum'. For example, '*/15' in the minute field means 'at minutes 0, 15, 30, and 45 of every hour'. In the hour field, '*/2' means 'every 2 hours: 0, 2, 4, … 22'.

What is the difference between day-of-month and day-of-week?

Day-of-month (DOM) targets a specific calendar date — e.g. the 1st or the 15th of each month. Day-of-week (DOW) targets a recurring weekday — e.g. every Monday. When both fields are set to non-wildcard values, most cron implementations fire when either condition is true (OR behaviour), which can be surprising. It is usually cleaner to set one to '*' and use the other.

Does the builder support @yearly, @monthly, or @reboot shortcuts?

The visual builder works with standard 5-field cron syntax. The @yearly, @monthly, @weekly, @daily, @hourly, and @reboot shorthands are shell-level aliases supported by cron daemons like crond, but they are not universal across all schedulers (GitHub Actions, Kubernetes CronJob, etc.). The equivalent 5-field expressions are available as presets.

How accurate are the 'Next 5 Scheduled Runs' times?

The next-run calculator uses your browser's local clock and timezone. It iterates minute-by-minute from the current time and checks each candidate against the cron expression — the same logic a cron daemon uses. Note that cron daemons typically do not account for Daylight Saving Time transitions, so a job scheduled for '0 2 * * *' may fire twice or not at all on DST change nights.

Does the tool send my cron expressions to a server?

No. All parsing, building, and scheduling logic runs entirely in your browser using JavaScript. Nothing is transmitted to any server. Your expressions are saved only in your browser's local storage for session persistence.

Cron Schedule Builder

Pick a plain-English preset or configure each field visually. Instantly generates the cron string, a human-readable description, and a preview of the next 5 runs.

Quick Presets

Minute(0–59)

Matches every minute. Cron token: *

Cron ExpressionPaste a cron string to parse it

translate

Every minute

*Minute

*Hour

*Day of Month

*Month

*Day of Week

1Thu, May 28, 2026, 03:18 PM
2Thu, May 28, 2026, 03:19 PM
3Thu, May 28, 2026, 03:20 PM
4Thu, May 28, 2026, 03:21 PM
5Thu, May 28, 2026, 03:22 PM

Field Reference

Field	Allowed values	Special chars	Example
Minute	0–59	* , - /	0 → at minute 0
Hour	0–23	* , - /	9 → 9:00 AM
Day of Month	1–31	* , - /	1 → 1st of month
Month	1–12	* , - /	*/3 → every quarter
Day of Week	0–6	* , - /	1-5 → Mon–Fri

* — every value, — list of values- — range/ — step interval

Why use our online Cron Schedule Builder?

Generate valid cron expressions visually or type them manually and see a plain-English explanation instantly. Useful for scheduling jobs in Linux, CI/CD pipelines, and cloud schedulers.

How to use Cron Schedule Builder

1
Pick a preset or start from scratch
Click any Quick Preset — such as 'Every Monday at 9 AM' or 'Daily at midnight' — to load a ready-made expression. Or leave the default and build your own from the field editors.
2
Configure each field visually
Click a field tab (MIN, HH, DOM, MON, DOW) to open its editor. Choose Every to match all values, Specific to pick exact values, Range for a continuous run of values, or Step (*/n) to fire every n units.
3
Read the plain-English description
As you adjust fields, the description updates instantly — for example: 'At 9:00 AM, Monday through Friday'. Use this to confirm the schedule matches your intent before deploying.
4
Check the next scheduled runs
The 'Next 5 Scheduled Runs' panel shows the upcoming fire times with full date and time. This lets you verify that edge cases like month boundaries or DST transitions behave as expected.
5
Copy the expression
Click Copy to place the cron string on your clipboard — paste it directly into your crontab, CI configuration, GitHub Actions schedule, or application scheduler.
6
Parse an existing cron string
Paste any 5-field cron expression into the expression input box. The builder will parse it, populate all field editors, and display the human-readable description so you can understand or modify it.

Cron expression syntax — a complete field reference

A standard cron expression has five space-separated fields: [minute] [hour] [day-of-month] [month] [day-of-week].

Minute: 0–59. Hour: 0–23 (0 = midnight). Day-of-month: 1–31. Month: 1–12 (or JAN–DEC). Day-of-week: 0–6 (0 = Sunday, 6 = Saturday; some implementations also accept 7 as Sunday).

Special characters: * matches every value. , separates multiple values (1,15 = 1st and 15th). - defines a range (9-17 = 9 AM to 5 PM). / defines a step (*/15 in minutes = every 15 minutes; 1-5/2 in day-of-week = every other day from Mon to Fri).

Examples: 0 9 * * 1-5 means every weekday at 9:00 AM. 0 0 1 * * means the 1st of every month at midnight. */30 * * * * means every 30 minutes. 0 0 * * 0 means every Sunday at midnight. 0 8 1,15 * * means the 1st and 15th of every month at 8 AM.

Where cron expressions are used — a developer's guide

Cron originated in Unix/Linux as the daemon that runs scheduled tasks. The crontab file (cron table) lists expressions alongside the commands to run. The standard 5-field syntax is used by virtually all Linux cron implementations.

Cloud and DevOps platforms have adopted cron as their scheduling language. GitHub Actions uses 5-field cron expressions in the schedule trigger (on: schedule: - cron: '0 0 * * *'). AWS EventBridge, Google Cloud Scheduler, and Azure Logic Apps all accept cron expressions for timer triggers. Kubernetes CronJob resources use the same 5-field format.

Many frameworks add a 6th field for seconds (0–59) at the start, making it [second] [minute] [hour] [day] [month] [day-of-week]. Spring Boot's @Scheduled annotation, Quartz Scheduler, and AWS Lambda's CloudWatch Events with second precision all use 6-field cron. Some implementations also add a 7th field for year. When a cron expression does not work as expected, check first whether the system expects 5 or 6 fields.

Common cron scheduling mistakes and how to avoid them

The most frequent cron mistake is misunderstanding the OR behavior when both day-of-month and day-of-week are set. The expression 0 0 1 * 1 runs at midnight on the 1st of the month OR every Monday — not only on Mondays that fall on the 1st. This is surprising and counter-intuitive. To avoid this, always set one of these two fields to * when using the other.

Timezone confusion is another common source of errors. Cron daemons typically run in the server's local timezone, which may differ from the user's timezone or UTC. A job scheduled for "9 AM" on a server in London will fire at 4 AM in New York. Cloud schedulers (GitHub Actions, Google Cloud Scheduler) run in UTC by default. Always check the timezone assumption and document it in your crontab or scheduler configuration.

DST transitions cause cron jobs to misbehave twice per year in regions that observe Daylight Saving Time. When clocks spring forward, a job scheduled for 2:30 AM may not fire that night (the clock jumps from 2:00 AM directly to 3:00 AM). When clocks fall back, a 1:30 AM job may fire twice. Schedule critical jobs at times that are not affected by DST transitions — midnight, noon, or any even hour in UTC.

Frequently Asked Questions

What is a cron expression?: A cron expression is a string of five space-separated fields that define when a recurring task should run: minute (0–59), hour (0–23), day-of-month (1–31), month (1–12), and day-of-week (0–6, where 0 is Sunday). For example, '0 9 * * 1' means 'at 9:00 AM every Monday'.
What does */n mean in a cron field?: The slash (/) is the step operator. '*/n' means 'every n units starting from the minimum'. For example, '*/15' in the minute field means 'at minutes 0, 15, 30, and 45 of every hour'. In the hour field, '*/2' means 'every 2 hours: 0, 2, 4, … 22'.
What is the difference between day-of-month and day-of-week?: Day-of-month (DOM) targets a specific calendar date — e.g. the 1st or the 15th of each month. Day-of-week (DOW) targets a recurring weekday — e.g. every Monday. When both fields are set to non-wildcard values, most cron implementations fire when either condition is true (OR behaviour), which can be surprising. It is usually cleaner to set one to '*' and use the other.
Does the builder support @yearly, @monthly, or @reboot shortcuts?: The visual builder works with standard 5-field cron syntax. The @yearly, @monthly, @weekly, @daily, @hourly, and @reboot shorthands are shell-level aliases supported by cron daemons like crond, but they are not universal across all schedulers (GitHub Actions, Kubernetes CronJob, etc.). The equivalent 5-field expressions are available as presets.
How accurate are the 'Next 5 Scheduled Runs' times?: The next-run calculator uses your browser's local clock and timezone. It iterates minute-by-minute from the current time and checks each candidate against the cron expression — the same logic a cron daemon uses. Note that cron daemons typically do not account for Daylight Saving Time transitions, so a job scheduled for '0 2 * * *' may fire twice or not at all on DST change nights.
Does the tool send my cron expressions to a server?: No. All parsing, building, and scheduling logic runs entirely in your browser using JavaScript. Nothing is transmitted to any server. Your expressions are saved only in your browser's local storage for session persistence.

Related Tools

swap_horiz

CI/CD Configuration Converter

Convert CI/CD pipelines between GitHub Actions, GitLab CI, CircleCI, and Bitbucket Pipelines. Parses workflows into a canonical IR and re-emits them with confidence-annotated audit, round-trip validation, and a Markdown audit report. 200+ component mappings (actions/checkout, setup-node, docker/build-push, AWS/GCP/Azure auth, CircleCI orbs, Bitbucket pipes). 100% in your browser.

schedule

Unix Timestamp

Unix timestamps to human dates, multiple timezones.

code

JSON Formatter

Clean, minify, and validate JSON data structures.

find_in_page

Regex Tester

Real-time expression matching and testing.

html

HTML Entity

Encode special chars to HTML entities and decode back.