/tools/cron-expression-generator
Cron Expression Generator
Explain Unix five-field schedules and enumerate their next runs in an IANA timezone, including daylight-saving transitions.
1. Expression
Generate, edit and calculate
2. Meaning
Human-readable schedule
3. Occurrences
Next runs
The next 10 runs appear here.
/syntax
Unix five-field cron reference
| Field | Allowed range | Examples |
|---|---|---|
| Minute | 0–59 | 0, */15 |
| Hour | 0–23 | 9-17 |
| Day of month | 1–31 | 1,15 |
| Month | 1–12 or names | jan-mar |
| Day of week | 0–7 or names | mon-fri; 0 and 7 are Sunday |
Lists, ranges and steps are supported, as are @yearly, @monthly, @weekly, @daily and @hourly.
/dialect
Deliberately Unix, not Quartz or EventBridge
This route accepts five fields and Vixie cron day semantics. It rejects a seconds field, Quartz ?, L, W and #, and AWS/EventBridge expressions with an explicit dialect error.
/dst
Timezone-aware enumeration
The worker enumerates UTC minutes and tests their local calendar representation. A nonexistent spring-forward time is skipped; a repeated fall-back wall time appears twice because it maps to two real instants. Calculation stops after five years and reports if the requested occurrences were not found.
/faq
Cron questions
What if both day fields are restricted?
Vixie OR semantics apply. A run occurs when either day-of-month or day-of-week matches, provided the time and month fields also match.
Does this install or run a cron job?
No. It only parses and previews a schedule locally; it never changes a server or sends the expression elsewhere.