ToolNest · Published 2026-09-24 · Updated 2026-09-24
Understanding five-field cron expressions
Cron looks cryptic until you map each field. The parser explains a standard five-field expression and lists upcoming local times.
The five fields
In order: minute (0–59), hour (0–23), day of month (1–31), month (1–12), day of week (0–6, Sunday first). Stars mean “every.” Commas list values. Hyphens are ranges. Slash is a step, as in */15.
What this parser does not do
No sixth seconds field, no @hourly aliases, no cron timezone prefixes. Day-of-month and day-of-week together use a simple combined match that can differ from some Unix crons. Treat the next-run list as a helper, then confirm in the environment that will actually schedule the job.
Questions
Why did minute 99 fail?+
It is outside 0–59. The parser rejects it instead of wrapping.