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Cron Expression Explainer online

Parse cron expressions and get a plain-English explanation

Cron Expression Explainer logo
by
CHUNKY
MUNSTER
minutehourdaymonthday of week

How to Use cron-expression

  1. Paste a cron expression (5 or 6 fields) into the input — e.g. 0 */6 * * *.
  2. Read the plain-English explanation: "every 6 hours at minute 0".
  3. See the next 10 scheduled run times in both UTC and your local timezone.
  4. Use the builder to construct an expression from dropdowns without writing cron syntax.

Cron expressions schedule recurring tasks by specifying minute, hour, day-of-month, month, and day-of-week fields — each accepting specific values, ranges, step syntax, and wildcards. Misreading a cron expression can cause jobs to run at the wrong time or not at all. This explainer translates any expression to plain English and shows the next scheduled runs.

Cron Field Syntax Reference

Standard cron: minute hour day-of-month month day-of-week. Each field accepts: a number, * (every), */n (every n), a-b (range), a,b,c (list), or L/W/# (extended Quartz syntax). Examples: 0 9 * * 1-5 — 9 AM on weekdays. */15 * * * * — every 15 minutes. 0 0 1 * * — midnight on the first of every month. 0 0 * * 0 — midnight every Sunday.

Frequently Asked Questions

What does */5 mean in cron?

*/5 means "every 5 units" — in the minute field, */5 means every 5 minutes (0, 5, 10, 15...). In the hour field it means every 5 hours.

What is the sixth field in cron expressions?

The optional sixth field is seconds (used in Quartz scheduler and some cloud platforms like AWS EventBridge and GCP Cloud Scheduler). Standard Unix cron has 5 fields; Quartz cron has 6 (seconds) or 7 (seconds + year).

How do I schedule a job for the last day of every month?

Standard cron cannot reliably do this because month lengths vary. Some extended implementations support L in the day-of-month field: 0 0 L * *. In standard cron, use a wrapper script that checks if tomorrow's month differs from today's.

Why does "0 9 * * 7" not run on Sundays on some systems?

Cron's day-of-week field is ambiguous: some systems treat 0 and 7 as Sunday; others only treat 0 as Sunday. For maximum compatibility, use 0 for Sunday (or the literal name sun where supported).

See also the Date Calculator and Unix Timestamp Converter for time-related developer tools.