What cron format does this use?

It uses the standard 5-field Unix format: minute, hour, day-of-month, month, and day-of-week. This is what crontab, most CI systems, and Kubernetes CronJobs expect, so the output drops straight in.

How are the fields ordered?

Left to right the fields are minute (0-59), hour (0-23), day of month (1-31), month (1-12), and day of week (0-6, where 0 is Sunday). An asterisk means every value for that field.

Is the human description accurate?

Yes. The description is generated from the actual field values, so it always reflects the expression shown. If you tweak the preset, the wording updates to match.

Does it support step and range syntax?

Yes. Presets like every 15 minutes use step syntax such as */15, and business-hours uses a range like 9-17 in the hour field. Both are valid standard cron and widely supported.

Will these work in Kubernetes and GitHub Actions?

Yes. Both use the same 5-field cron syntax. Note that some platforms run in UTC, so confirm your scheduler's timezone before relying on a specific local hour.

What is the Cron Expression Generator?

Build valid 5-field cron expressions for common schedules: hourly, daily, weekly, monthly, and business hours. Each expression comes with a plain-English description so you can configure schedulers with confidence. It runs free in your browser on Gera Tools, with nothing uploaded.

Cron Expression Generator

Name: Cron Expression Generator
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

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What this tool does

The Cron Expression Generator produces valid 5-field cron expressions for the schedules people actually need — hourly, every few minutes, daily at a time, weekly on a day, monthly on a date, and weekday business hours — each paired with a clear English description. It turns “I think the fields go minute, hour, day…” into a copy-paste-ready schedule.

How it works

A cron expression has five space-separated fields: minute, hour, day-of-month, month, and day-of-week. The generator builds each preset by filling the relevant fields and leaving the rest as * (every value). For example, daily-at-time sets a minute and hour with * for the date fields; every-15-minutes uses the step form */15 in the minute field; business-hours uses the range 9-17 in the hour field and 1-5 (Mon–Fri) in day-of-week. The human-readable line is derived directly from those field values, so it always matches the expression.

All generation happens locally in your browser.

Understanding the five fields

  minute   hour   day-of-month   month   day-of-week
  ──────   ────   ────────────   ─────   ───────────
  0-59     0-23   1-31           1-12    0-6 (0=Sun)

An asterisk (*) in any field means “every valid value for that field.” The most common special characters beyond *:

Character	Meaning	Example
`*/n`	Every n units	`*/15` in minute = every 15 minutes
`a-b`	Inclusive range	`9-17` in hour = 9 am through 5 pm
`a,b,c`	List of values	`1,3,5` in day-of-week = Mon, Wed, Fri
`a/n`	Starting at a, every n	`0/30` in minute = at :00 and :30

Common expressions with explanations

0 * * * *          Every hour, on the hour
*/15 * * * *       Every 15 minutes
0 9 * * 1-5        At 9 am, Monday through Friday
0 0 1 * *          At midnight on the first of every month
0 2 * * *          At 2 am every day (common for nightly batch jobs)
30 8 * * 1         At 8:30 am every Monday
0 9-17 * * 1-5     Every hour during business hours on weekdays

Timezone gotcha

Cron runs in the timezone of the system or scheduler interpreting it. This causes real bugs:

Linux crontab uses the system timezone, which is often UTC on servers.
GitHub Actions runs in UTC by default.
Kubernetes CronJob also uses UTC.
Railway and most hosted platforms run in UTC.

If you want a job to run at 9 am London time and the scheduler uses UTC, you need to account for the offset (0 or +1 in summer). Always document the timezone assumption next to the expression — future-you will thank present-you.

Where these expressions work

The standard 5-field syntax is supported by:

Unix/Linux crontab
GitHub Actions (on.schedule.cron)
Kubernetes CronJob (spec.schedule)
AWS EventBridge scheduled rules (uses the same syntax)
Most task schedulers and hosted cron services

Some platforms (AWS CloudWatch Events, Google Cloud Scheduler) use a 6-field format adding seconds or years. The expressions here are 5-field only.