Crontab Schedule Explainer

Enter cron expressions and see human-readable schedule descriptions with next execution time predictions.

Tested tool guide Tested browser tools Checked August 16, 2026

What Crontab Schedule Explainer does and how it behaves

Crontab Schedule Explainer reads a crontab-style schedule, translates its five fields into plain language, and predicts upcoming matching times. The fields represent minute, hour, day of month, month, and day of week, in that order. The most common mistake is supplying a seconds field: standard five-field crontab syntax starts with minutes, so a six-field expression from another scheduler can be rejected or interpreted differently.

How the result is produced

Field interpretation

The explainer interprets each position according to five-field crontab syntax. An asterisk allows every value in that field, commas combine values, hyphens specify ranges, and a slash introduces a step. The resulting description expresses how those constraints combine, such as selected minutes during particular hours or weekdays.

Execution predictions

After interpreting the fields, the tool identifies upcoming calendar times that satisfy the expression. These predictions make combinations such as month boundaries, weekday restrictions, and stepped minutes easier to inspect than a description alone. They describe scheduled matches, not confirmation that a cron daemon actually launched or completed a command.

Good uses

Check whether `17 2 * * 1-5` represents the intended weekday maintenance window before adding it to a crontab.
Inspect the next occurrences of `*/15 9-17 * * 1-5` to confirm how a stepped minute field interacts with working hours and weekdays.
Translate an inherited schedule into readable terms while diagnosing why an expected calendar time does not match its expression.

Limits and checks

Confirm that the source scheduler uses five-field crontab syntax. Quartz-style schedules and other dialects may add a seconds or year field and use different operators.
Read predicted times in the timezone presented by the tool, then compare that with the cron host's timezone. Daylight-saving transitions can skip or repeat local wall-clock times.
Treat the result as an explanation of the schedule only. It does not validate the command, shell quoting, environment variables, file permissions, daemon state, or whether a previous job is still running.

Common questions

Will the predicted times exactly match my server?

Not necessarily. The cron host may use a different timezone, daylight-saving rule, or cron dialect from the context used for the displayed prediction. The server also must have the crontab installed and its scheduler running. Compare the tool's interpreted fields and displayed time basis with the host configuration before relying on the dates.

Why does `0 9 1 * 1` run more often than the first Monday of each month?

Under traditional crontab semantics, restricting both day of month and day of week creates matches when either field matches, provided the minute, hour, and month also match. This expression therefore selects 09:00 on every Monday and on the first day of every month. It does not mean only the first Monday.

References and verification

The behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.