How many fields does a cron expression have?

Standard Unix cron uses five fields: minute, hour, day-of-month, month and day-of-week. Quartz adds a leading seconds field and an optional trailing year field, giving six or seven. AWS EventBridge uses six fields with a required year.

What does an asterisk mean in cron?

An asterisk (*) means every value in that field. So * in the minute field means every minute, and * in the month field means every month. Combine it with a step like */15 to mean every 15th value.

How do I run a job only on weekdays?

Use a range or list in the day-of-week field. 0 9 * * 1-5 runs at 09:00 Monday through Friday, where 1 is Monday and 5 is Friday in standard cron (0 and 7 both mean Sunday).

What is the question mark in Quartz cron?

In Quartz and AWS cron, ? means no specific value and is used in the day-of-month or day-of-week field when the other one is set. It avoids a conflict, since you usually constrain a schedule by one of the two, not both.

Does the decoder account for special characters like L and W?

The reference lists L (last), W (nearest weekday) and # (nth weekday), but the plain-English preview applies the standard five-field semantics and does not expand those Quartz-only modifiers. Use it as a guide, then verify against your scheduler.

Cron Expression Reference

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This is an interactive cron expression reference and decoder. Type a cron string and it explains, in plain English, when the job will run. It supports the three dialects you meet in practice: standard five-field Unix cron, Quartz (with a seconds field), and AWS EventBridge — and lists every field’s range and the special characters each accepts.

How it works

A cron expression is a row of space-separated fields, each describing one unit of time. Standard cron reads as minute hour day-of-month month day-of-week. Each field accepts a single value, a list (1,15), a range (9-17), a step (*/15 meaning every 15th unit), or * for every value. The decoder splits your expression on whitespace, validates the field count for the chosen format, and translates each field into words — for example 0 9 * * 1-5 becomes “at minute 0, hour 9, on day-of-week Monday through Friday.” Quartz adds a leading seconds field and an optional year; AWS EventBridge requires a year and uses ? to avoid a day-of-month versus day-of-week conflict.

Special characters and examples

Beyond the basics, schedulers add modifiers: ? (no specific value), L (last day or last weekday), W (nearest weekday to a date), and # (the nth weekday of the month, e.g. 6#3 for the third Friday). The reference table lists these per field. The examples section gives ready-made expressions — every five minutes, hourly, daily at midnight, weekday mornings — that you can click to load and adapt. Everything runs in your browser; nothing is uploaded.