Cron Explainer

About this tool

Cron expressions are compact but hard to read. Paste a standard 5-field cron schedule — minute, hour, day-of-month, month, day-of-week — and get a plain-English description of when it runs. Supports *, steps like */5, ranges like 1-5 and lists. Runs in your browser.

Common use cases

• Understand cron schedules — Decode cron expressions to understand when a scheduled job will run
• Debug cron jobs — Verify that your cron expression matches the intended schedule
• Learn cron syntax — Practice reading and writing cron expressions for Linux and cloud schedulers

How it works

A cron expression has 5 space-separated fields: minute (0-59), hour (0-23), day of month (1-31), month (1-12), and day of week (0-6, Sunday=0). Each field can contain a number, range (1-5), list (1,3,5), step (*/5), or wildcard (*). The explainer parses each field, determines the set of valid values, and generates a human-readable description of when the job will run. For example, "0 9 * * 1-5" means "at 9:00 AM every weekday (Monday through Friday)".

FAQ

What are the five fields?

In order: minute (0–59), hour (0–23), day of month (1–31), month (1–12), and day of week (0–6, Sunday=0).

Does it support step and range syntax?

Yes — it understands *, */n steps, m-n ranges, and comma lists, and names months and weekdays.

Which cron flavor?

Standard 5-field cron used by crontab, most schedulers and CI systems (not the optional seconds field).

What is the difference between cron and systemd timers?

Cron is the traditional Unix scheduler with a simple 5-field syntax. Systemd timers are more modern, support calendar events and monotonic timers, have better logging, and can depend on other services. Both are widely used on Linux.

How do I run a cron job every 5 minutes?

Use */5 in the minute field: */5 * * * *. This runs at minutes 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55 of every hour.