Cron Expression

What does this tool do?

Cron Expression has two modes. Explain validates a cron schedule, explains it in plain English and shows the next executions as real dates in your timezone. Build constructs an expression from common frequencies — every N minutes, daily, weekly and so on — and immediately explains it and lists the next runs. Everything is computed locally in your browser.

The five (and six) fields

A classic cron expression has five fields:

A six-field expression prepends seconds (0–59). This tool accepts exactly five or six fields. A seventh (year) field is not supported, and neither is @reboot, because it has no regular schedule.

Field syntax

• * means every value.
• */5 means every fifth value (a step).
• 1-5 is a range.
• 1,3,5 is a list.
• 1-5/2 combines a range and a step.

Day of month and day of week

When both day-of-month and day-of-week are restricted, this tool follows the standard (Vixie) semantics and treats them as an OR: the expression fires on either match. 0 0 1 * 0 runs at midnight on the 1st of the month and every Sunday.

Extensions: L, W, # and ?

Beyond classic cron, this tool supports common extensions:

• L — the last day of the month.
• W — the nearest weekday to a given day.
• # — the nth weekday of a month (5#3 = third Friday).
• ? — “no specific value”, treated as * for that field.

These are extensions, not part of plain POSIX cron. They are supported consistently here and explained in the result.

Aliases

@yearly, @annually, @monthly, @weekly, @daily, @midnight and @hourly are accepted shortcuts. @reboot is not, because it does not represent a regular schedule.

Build mode

If you do not know cron syntax, switch to Build. It generates an expression from common schedules:

• Every minute
• Every N minutes
• Hourly
• Daily
• Weekly (pick the weekdays)
• Monthly (pick the day of the month)
• Yearly (pick the month and day)

Each change updates the expression, its explanation and the next runs immediately. The builder covers these common patterns only — it is not a way to represent every possible cron expression. For anything beyond them, switch to Explain and type the expression directly.

Timezone and DST

Runs are shown in a real IANA timezone (your browser timezone by default, or any you choose). Daylight saving transitions are handled correctly: a time that does not exist on a spring-forward day is shifted forward, and a time that occurs twice on a fall-back day is reported once.

Examples

• */5 * * * * — every five minutes.
• 0 9 * * 1-5 — at 09:00, Monday through Friday.
• 0 0 1 * * — at midnight on the first day of each month.
• 30 14 15 6 * — at 14:30 on June 15.
• 0 0 L * * — at midnight on the last day of each month.

Privacy

Your expression is validated and expanded locally. Nothing is uploaded or sent anywhere.