Why does my cron expression parser say the schedule is invalid?

The field count or token set probably does not match the parser mode. A 5-field parser will reject 6-field input, and Quartz-style tokens like `?`, `L`, `W`, and `#` are not valid in standard cron.

Why does cron to human readable output look slightly different from another tool?

Human-readable descriptions are interpretive. Different tools choose different wording, default assumptions, and dialect rules while still describing the same underlying schedule.

Why is `0 0 1 * 1` confusing?

Some cron systems treat day-of-month and day-of-week as an OR-style match, not a strict AND. That means the job may run on the first day of the month and on Mondays, not only when both are true.

Why do next-run times look wrong around daylight saving changes?

Cron schedules are evaluated in a timezone, and DST can skip or repeat local times. A preview is helpful, but you still need to verify behavior in the scheduler's actual timezone.

Can I trust the plain-English explanation as the final answer?

Use it as a review aid, not as a substitute for testing. The safest workflow is: parse the expression, read the explanation, then validate it in the target scheduler or staging environment.

Cron Expression Parser

Explain a cron schedule and inspect upcoming run times locally in your browser.

Cron dialect

Preview timezone

Cron expression

minute hour day-of-month month day-of-week | Ctrl/Cmd+Enter parses | Ctrl/Cmd+K clears

Inspector notes

Selected field style

Standard 5-field

minute hour day-of-month month day-of-week

Timezone context

Schedule previews are calculated in UTC.

A second column always shows what the same run looks like in your browser timezone, UTC.

Support scope

Best for standard cron numbers or JAN-DEC / SUN-SAT names, plus ranges, lists, and steps. Quartz-only tokens like?, L, W, and # are intentionally out of scope here.

DST and day-field caveats

Preview rows are real future timestamps for the selected timezone. DST transitions can skip or repeat wall-clock hours, and when both day-of-month and day-of-week are restricted this tool follows standard cron OR semantics.