Cron Parser

A cron expression is a compact, five-field string that tells a Unix-like scheduler exactly when to fire a recurring job. The name comes from chronos (Greek for time), and cron daemons have powered scheduled automation on Linux and macOS servers since the 1970s. Today the same syntax drives cloud functions, CI/CD pipelines, database maintenance windows, and application-level task queues.

Every cron expression contains exactly five whitespace-separated fields:

The cron parser on this page reads your expression, breaks it into those five fields, translates each one into plain English, and then walks forward minute-by-minute from the current time to display the next five scheduled run times. This makes it easy to verify that your schedule is correct before deploying it to production.

Each field in a cron expression supports four special characters that give the syntax its expressive power. Understanding how each character is matched is the key to writing reliable schedules.

• Asterisk (*) — matches every value in the field's range. * * * * * fires every minute of every day.
• Step (/) — combined with a range or * to fire at regular intervals. */15 in the minute field fires at minutes 0, 15, 30, and 45. 2/3 fires at 2, 5, 8, … up to the field maximum.
• Range (-) — selects a contiguous span of values. 1-5 in the weekday field means Monday through Friday.
• List (,) — selects an explicit set. 8,17 in the hour field fires at 8 AM and 5 PM.

Parsing happens left-to-right: the parser splits the expression on whitespace and processes each field independently. For the month and day-of-week fields it also translates numeric values to names (e.g., month 3 becomes March, weekday 1 becomes Monday).

One of the most misunderstood parts of standard cron is how the day-of-month and day-of-week fields interact when both are set to non-wildcard values. This cron parser follows the same logic used by Vixie cron (the reference implementation on most Linux systems):

• If either day-of-month or day-of-week is *, only the other field is evaluated — effectively an AND with a wildcard.
• If both fields contain specific values (non-*), the scheduler fires when either condition is true — a logical OR.

For example, 0 0 1 * 5 fires at midnight on the 1st of every month and also at midnight every Friday, not only on Fridays that happen to be the 1st. This OR behavior surprises many developers expecting AND semantics. To guarantee a job only runs on a specific weekday, use * for day-of-month; to guarantee it runs only on a specific date, use * for day-of-week.

The cron next-run calculator on this page applies exactly this OR/AND logic when computing future fire times, so you can see the effect directly in the "Next 5 Run Times" output.

The following table lists the most frequently used cron expressions across web development, DevOps, and data engineering workflows. Each entry shows the raw expression, its human-readable meaning, and a practical use case.

Paste any expression from this table directly into the parser above to see its field breakdown and next scheduled runs. Knowing these building-block patterns by heart dramatically speeds up writing new schedules from scratch.

This free online cron parser is designed for developers, system administrators, and DevOps engineers who need to verify scheduled tasks quickly and confidently. Here is how to get the most out of it.

1. Type or paste your cron expression into the input box. The parser accepts any standard five-field expression and updates results in real time as you type.
2. Read the human-readable summary in the blue gradient box. This sentence-level translation is generated from each field's parsed value and tells you exactly when the job fires in plain English. Use the Copy button to grab the description for documentation.
3. Check the field breakdown table. Each of the five fields is shown alongside its parsed meaning. This is useful for spotting typos — for example, confirming that 1-5 in the weekday field correctly resolves to "Monday to Friday" rather than an unexpected range.
4. Review the next five run times. The calculator walks forward from the current moment, checking each minute against the expression, and surfaces the next five matching timestamps. This is the most reliable way to confirm that a schedule will fire when you expect.
5. Click any example expression at the bottom of the calculator to load it instantly and see how common patterns parse.

The parser validates that your expression has exactly five fields. If you enter fewer or more fields it will display a clear error message, so you can correct the expression before deploying it. This is especially helpful when migrating expressions between tools that may use six-field formats (which add a seconds field) versus the standard five-field crontab format.