Does this tool run my cron job?

No. It parses the expression and calculates upcoming times locally. Your actual scheduler is responsible for executing jobs.

Are six-field cron expressions detected automatically?

No. Select With seconds 6 fields explicitly so the first value cannot be mistaken for a minute field.

What happens when day of month and day of week are both set?

This parser uses Vixie cron OR semantics: a matching value in either restricted day field qualifies. Other schedulers may differ.

How does daylight saving time affect a schedule?

The selected IANA timezone supplies DST rules. Times that do not exist during a forward jump are skipped, and overlaps are listed once at the first occurrence.

Will this expression work in Quartz or AWS EventBridge?

Not necessarily. Those systems use different field counts and special characters. Check the documentation for the scheduler where the expression will run.

Developer

Cron Expression Parser

Parse and validate Unix cron expressions, build common schedules, explain each field, and inspect the next run times in local, UTC, and ISO formats.

Your cron expressions are processed locally in your browser.

Cron expression

Interpretation

Enter a schedule to inspect itThe field breakdown and next run times will appear here.

Next 10 runsTimezone

No run times yetValid expressions are evaluated from the current time.

Your cron expressions are processed locally in your browser.

How to use it

Choose Standard 5 fields or the explicit With seconds 6 fields syntax.
Enter an expression to parse it, or use Build and a preset to create one with structured controls.
Review the field meanings and ten upcoming runs in browser local time, UTC, or a selected IANA timezone.

Example

Input

*/15 9-17 * * 1-5

Output

Every 15 minutes, from 09:00 through 17:59, Monday through Friday.

Parse and build cron expressions

Cron expressions describe recurring schedules for jobs, maintenance tasks, and automation. Parse mode validates an existing expression, while Build mode creates common schedules with structured controls and presets.

The five Unix cron fields

A standard expression contains minute, hour, day of month, month, and day of week. The optional six-field mode in this tool adds seconds at the beginning and must be selected explicitly.

Wildcards, lists, ranges, and steps

An asterisk matches every value, commas select a list, a hyphen defines a range, and a slash applies a step. For example, */15 means every 15 units and 1-5 in day of week means Monday through Friday.

Day matching semantics

This parser follows Vixie cron behavior: when both day of month and day of week are restricted, a date matches when either field matches. Confirm this behavior with the scheduler that will run the expression.

Timezones and daylight saving time

IANA timezone rules account for daylight saving changes. A local time inside a DST gap may not run, while an overlapping local time is shown once at its first occurrence.

Unix cron is not Quartz cron

Unix cron implementations differ from Quartz, AWS EventBridge, and systemd timers in field order, weekday numbering, and special syntax. This tool intentionally does not claim compatibility with those schedulers.

Common questions

Does this tool run my cron job?: No. It parses the expression and calculates upcoming times locally. Your actual scheduler is responsible for executing jobs.
Are six-field cron expressions detected automatically?: No. Select With seconds 6 fields explicitly so the first value cannot be mistaken for a minute field.
What happens when day of month and day of week are both set?: This parser uses Vixie cron OR semantics: a matching value in either restricted day field qualifies. Other schedulers may differ.
How does daylight saving time affect a schedule?: The selected IANA timezone supplies DST rules. Times that do not exist during a forward jump are skipped, and overlaps are listed once at the first occurrence.
Will this expression work in Quartz or AWS EventBridge?: Not necessarily. Those systems use different field counts and special characters. Check the documentation for the scheduler where the expression will run.