Understand five-field cron expressions with a plain-language explanation, expanded field values and five upcoming UTC matches. Check schedules locally without creating or running jobs.
Your expressions are parsed on your device without uploads, external APIs or saved history. The tool provides a bounded calendar preview and an explicit day-field rule, so you can inspect the schedule before applying it elsewhere.
This is a limited five-field Unix/Cronie-style explainer: minute, hour, day-of-month, month, day-of-week. It supports numeric lists, ascending ranges, and steps on * or a range. Three-letter month and weekday names are case-insensitive. Sunday accepts 0 or 7. Common calendar macros expand to five fields. Other cron implementations may differ; validate in your target scheduler.
Seconds and year fields, commands, environment assignments, Quartz/AWS syntax such as ?, L, W and #, random ~ ranges, @reboot, wrapping ranges, single-number steps and wildcard/list mixtures are rejected. Input is limited to 512 characters. Steps must be positive integers no larger than that field’s numeric span. This is an explanation tool, not a complete crontab-file validator.
In this supported subset, if either day field begins with *, including a stepped wildcard, both day fields must match. Otherwise day-of-month OR day-of-week may match. An explicit full numeric range is still treated as a restricted day field. This distinction is shown in every report; do not assume both restricted fields are combined with AND.
No. A step selects values within its field and resets at its boundary. For example, */35 in the minute field selects 00 and 35 each hour, rather than a continuous 35-minute interval. Range steps start from the lower endpoint. The field table shows the exact selected values.
The preview uses UTC only and returns at most five matching minute boundaries strictly after the reference, searching up to eight years ahead. No matches in that window does not prove that a schedule is impossible. The optional reference accepts UTC years 1970–9990. A blank reference snapshots the device clock; Use current UTC fills the current minute. Actual scheduler timezone, daylight-saving behavior and dialect can differ.
No. This website only explains expressions and produces a downloadable text report. It never creates jobs, executes commands, changes system settings or stores your expression. Use your scheduler separately to install a job after checking its documentation.
