Cron Expression Parser & Generator

What is Cron Parser?

A cron expression is a compact schedule used by Unix cron, Kubernetes CronJobs, CI systems, and cloud schedulers. Its five fields — minute, hour, day-of-month, month, day-of-week — are terse and easy to get wrong. This parser translates any expression into plain English and previews the next few run times so you can confirm a schedule does what you intend before deploying it.

How to read a cron expression

1. 1Enter a 5-field cron expression, e.g. */15 * * * *.
2. 2Read the plain-English explanation of when it runs.
3. 3Check the list of upcoming run times to confirm the schedule.
4. 4Adjust the fields until the preview matches your intent.

Use Cases

Code Examples

*/15 * * * *   every 15 minutes
0 9 * * 1-5    09:00, Mon–Fri
0 0 1 * *      midnight on the 1st
0 */6 * * *    every 6 hours

Key Concepts

The five fields

In order: minute (0-59), hour (0-23), day-of-month (1-31), month (1-12), day-of-week (0-6, Sun=0). An asterisk means 'every'.

Step and range

*/5 means 'every 5'. 1-5 is a range. 1,15 is a list. Combine them: 0-30/10 runs at 0, 10, 20, 30.

Timezone

Cron runs in the server's timezone. Most production servers use UTC, so a '9am' schedule may not be 9am locally.

Tips & Best Practices

• ▸Day-of-month and day-of-week are OR-combined when both are set — a classic gotcha that fires more often than expected.
• ▸Servers usually run in UTC; convert your intended local time before writing the expression.
• ▸The optional 6th 'seconds' field (Quartz, some cloud schedulers) is not standard Unix cron — check your platform.
• ▸Prefer */N steps over long comma lists for readability (*/15 beats 0,15,30,45).