Cron Expression Parser

How to Use

Type a standard 5-field cron expression (minute, hour, day-of-month, month, day-of-week) or click a preset. The tool shows a table explaining each field and lists the next 5 run times in UTC. Adjust the expression and the breakdown updates instantly.

Why This Tool Is Useful

Cron syntax is powerful but famously hard to read — five terse fields packed with asterisks, slashes, and ranges. A tiny mistake can make a job run every minute instead of once a day, or never run at all. This parser turns the expression into plain English and, crucially, shows the actual next run times so you can confirm the schedule does what you intended before you deploy it.

The Five Cron Fields

A standard cron expression has five fields separated by spaces: minute (0–59), hour (0–23), day of month (1–31), month (1–12), and day of week (0–6, where 0 is Sunday). Each field accepts an exact value, a range like 1-5, a list like 1,15,30, a step like */10 (every 10 units), or * for 'every'.

The Day-of-Month / Day-of-Week Rule

One quirk trips up almost everyone: when both the day-of-month and day-of-week fields are restricted (neither is *), cron runs when either matches, not both. So '0 0 1 * 1' runs at midnight on the 1st of the month AND every Monday. If you only want Mondays, leave day-of-month as *. This parser follows that standard behavior when computing next run times.

Steps, Ranges, and Lists

The field syntax combines a few building blocks:

• * — every value (every minute, every hour, and so on).
• */n — every n units, e.g. */15 in minutes = :00, :15, :30, :45.
• a-b — a range, e.g. 1-5 in day-of-week = Monday to Friday.
• a,b,c — a specific list of values.
• Combine them: 0,30 9-17 * * 1-5 = every half hour, 9am–5pm, weekdays.

Common Cron Expressions