Cron Expression Explainer

Paste a crontab schedule and read what it means in plain English, field by field, along with the next times it will fire. Standard five-field syntax is supported, including lists, ranges, steps, month and weekday names and the @daily-style shortcuts, and the run times can be shown in your own time zone or in UTC to match the server.

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Explain a Cron Expression

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How to Use the Cron Explainer

Type or paste a cron expression such as */15 9-17 * * 1-5.
Choose whether run times are shown in your local time or UTC.
Read the description, the field breakdown and the list of upcoming runs.

About This Tool

Developers and system administrators writing crontab entries, CI schedules, Kubernetes CronJobs or cloud scheduler rules, and anyone inheriting a schedule they need to understand.

Input: 5-field cron expression or @macro · Output: Plain-English description and run times.

Features and Limitations

Features

Lists, ranges, steps (*/5, 10-30/10) and names (JAN–DEC, MON–SUN).
Follows standard cron behaviour: when both day-of-month and day-of-week are restricted, either can match.
Shortcuts @yearly, @annually, @monthly, @weekly, @daily, @midnight and @hourly.
Clear error messages that name the field and the value that is out of range.

Limitations

Quartz and Spring extensions (seconds field, L, W, # and ?) are not supported and are reported as errors.
Run times are calculated in your browser's time zone or UTC; the server may use a different zone, and daylight-saving changes can skip or repeat runs.
@reboot runs at start-up, so it has no run times to list.
Results are computed in your browser; nothing you enter is sent to a server.

Example

*/15 9-17 * * 1-5 means every 15 minutes from 09:00 to 17:45, Monday to Friday, so a run at 17:45 is the last of the day.

Frequently Asked Questions

What do the five fields mean?

Minute (0–59), hour (0–23), day of month (1–31), month (1–12) and day of week (0–6, where 0 and 7 are Sunday).

Why does my job run on more days than expected?

If both day-of-month and day-of-week are set (not *), cron runs when either matches. 0 0 1 * 1 runs on the 1st of each month and on every Monday.

What time zone does cron use?

The system time zone of the server, unless your crontab or scheduler sets CRON_TZ or TZ. Cloud schedulers often default to UTC.

How do I run a job every 90 minutes?

Standard cron cannot express it in one line because steps restart each hour or day. Use two entries, such as 0 0-21/3 * * * and 30 1-22/3 * * *.