What does * * * * * mean?

`* * * * *` means every minute of every hour of every day — 1,440 executions per day. Practical examples: `0 * * * *` runs once every hour at minute 0. `0 2 * * *` runs once daily at 02:00. `*/5 * * * *` runs every 5 minutes. `0 9 * * 1-5` runs weekdays at 09:00. The five positions represent minute, hour, day-of-month, month, and day-of-week — in that order.

What is the difference between 5-field and 6-field cron?

Standard Unix cron (and most schedulers: Linux crontab, GitHub Actions, Vercel, Railway) uses 5 fields: minute, hour, day, month, weekday. AWS EventBridge and Quartz Scheduler extend this with a 6th field — seconds (placed before minute) or year (placed after weekday). This builder generates standard 5-field cron compatible with crontab, GitHub Actions, and Vercel cron configuration.

How do I run a job every 15 minutes?

Use `*/15 * * * *`. The step notation `*/N` means every Nth value in the range. `*/15` in the minute field runs at minutes 0, 15, 30, and 45 — four times per hour. More examples: `*/30 * * * *` runs every 30 minutes. `0 */6 * * *` runs every 6 hours at the top of the hour. `*/10 9-17 * * 1-5` runs every 10 minutes during business hours, Monday–Friday only.

Can cron run on a specific weekday?

Yes. Day-of-week values: 0 or 7 = Sunday, 1 = Monday, through 6 = Saturday. `0 9 * * 1` runs at 09:00 every Monday. `0 9 * * 1-5` runs Monday through Friday at 09:00. `0 9 * * 1,3,5` runs Monday, Wednesday, and Friday. Important: if both day-of-month and day-of-week fields are set to non-`*` values, cron runs when either condition is true — not both.

How do day-of-month and day-of-week interact?

When both day-of-month and day-of-week are restricted (neither is `*`), most cron implementations trigger when either condition matches — not both. For example, `0 9 1 * 1` runs at 09:00 on the 1st of every month AND on every Monday — not only on Mondays that fall on the 1st. To avoid surprises, set only one of the two fields and leave the other as `*`.

Does the cron builder send my data anywhere?

No. The expression is built, explained, and previewed entirely in your browser using JavaScript. Nothing is uploaded, logged, or stored on any server. It is safe to build and test schedules for private infrastructure without leaving your browser.

developer

Free Cron Expression Builder — Visual Cron Schedule Generator

A cron expression is a string of five fields that defines a recurring schedule: minute, hour, day of month, month, and day of week. This builder lets you set each field visually and generates the correct cron string with a plain-English explanation of when the job will run.

Free — No SignupRuns in BrowserData Never UploadedPopular tool

developer

Build cron schedules visually and get the expression + plain-English explanation.

Build cron expressions field by field with visual inputs
One-click presets for common schedules (hourly, daily, weekdays, monthly)
Plain-English explanation of any cron string — confirms the schedule at a glance
Preview of the next five run times in your local timezone
Supports all special characters: *, /, ranges (-), and lists (,)
Compatible with Linux crontab, GitHub Actions, Vercel Cron, and Kubernetes CronJobs
Client-side only — nothing is uploaded or stored

Features

Everything you need in one Cron Expression Builder

Visual cron schedule builder

Set each of the five cron fields independently and watch the expression assemble itself — no need to memorize the syntax of *, /, -, and ,.

Plain-English cron explainer

Every expression is translated into a readable sentence such as "At 09:00, Monday through Friday" so you can confirm the schedule at a glance.

Next run preview

The tool computes and lists the next five times the job will run in your local timezone — the fastest way to catch a schedule that is off by an hour or a day.

Works with every scheduler

The standard 5-field output is compatible with Linux crontab, GitHub Actions, Vercel Cron, Kubernetes CronJobs, and most modern job runners.

How It Works

How to use Cron Expression Builder

Set each field

Choose values for minute, hour, day, month, and weekday using dropdowns or custom input.

See the expression

The cron string updates in real time. Copy it for use in Vercel, GitHub Actions, Linux crontab, or any scheduler.

Read the explanation

The plain-English summary tells you exactly when the job will run — e.g. "Every day at 02:00 UTC".

Format Comparison

Cron special characters — syntax reference

Character	Meaning	Example
*	Every value in the field	* * * * * — every minute
*/n	Every nth value (step)	/15 * * * — every 15 minutes
a-b	A range of values	0 9-17 * * * — hourly from 9am to 5pm
a,b,c	A list of specific values	0 0 1,15 * * — the 1st and 15th of each month
a-b/n	Stepped range	0 0-23/2 * * * — every 2 hours

Troubleshooting

How to fix common syntax errors

Most “invalid JSON” failures come from a small set of mistakes. Paste the failing JSON above, click Validate, and the tool points you at the exact line and column.

Both day-of-month and day-of-week set0 9 1 * 1

When neither field is *, cron fires when either matches (OR logic). Use only one of the two fields and set the other to * to get the schedule you intend.

Using 6-field format on a 5-field scheduler0 */15 * * * *

Linux crontab, GitHub Actions, and Vercel expect exactly 5 fields. The leading seconds field used by Quartz/Spring will be treated as the minute field, shifting every value one position.

Timezone confusion0 9 * * * (expects 9am local)

Cron runs in the server's system timezone, not your local timezone. Convert your desired time to UTC (or the server TZ) before setting the hour field.

*/1 instead of **/1 * * * *

*/1 is syntactically valid but redundant — it means every 1 value, which is the same as *. Use * directly for clarity.

Day-of-week numbering mismatch0 9 * * 7 (expects Sunday)

Most schedulers accept both 0 and 7 for Sunday, but some (Quartz, Kubernetes) use 1-based numbering where 1=Sunday and 7=Saturday. Check your scheduler's documentation.

Month as 0-indexed0 0 1 0 * (expects January)

Standard cron uses 1–12 for months (1=January). Some non-standard implementations use 0–11. If your job never runs in January, change month field 0 to 1.

FAQ

Frequently asked questions

A cron expression is a space-separated string of five fields that defines a recurring schedule: 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). Special characters enable flexible patterns: `*` matches any value, `/` defines steps (every Nth), `,` separates multiple values, and `-` specifies ranges.

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References

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