Cron Expression Generator
Click the day-and-hour grid to build a cron expression visually. The tool emits 5-field Vixie syntax (and 6-field Quartz on toggle), compresses lists to ranges and steps, and previews the next five fire times.
Quick Conversion
Formula: runs/day = hours selected × 1
Preset recipes
Cron quick reference
| Syntax | Meaning |
|---|---|
| * | every value in field |
| 5 | exact value 5 |
| 1-5 | range 1 through 5 (inclusive) |
| 1,3,5 | list — 1, 3, and 5 |
| */15 | every 15 starting from min |
| 0-30/5 | every 5 within 0-30 |
| @hourly | = 0 * * * * |
| @daily | = 0 0 * * * |
| @weekly | = 0 0 * * 0 |
| @monthly | = 0 0 1 * * |
Need to parse an existing expression? Cron parser.
Output composition
expr = <minute> SP <hour> SP "*" SP "*" SP <dow>
= compact(minutes) " " compact(hours) " * * " compact(days)Worked: selected days = Mon-Fri (1,2,3,4,5) → "1-5". Selected hour = 9 → "9". Minute = 0 → "0". Result: "0 9 * * 1-5".
How to build a cron expression visually
- 1Click the day pills (Sun-Sat) to choose which weekdays your job should fire on. Empty = every day.
- 2Click the hour buttons (00-23) to select firing hours. Empty = every hour.
- 3Set the exact minute, or use the 'every N min' input to express '*/5', '*/15', etc.
- 4Toggle '6-field (Quartz)' if your scheduler (AWS, Spring) requires a seconds field — the tool prepends '0'.
- 5Verify the next-fires preview matches your intent, then click the copy icon next to the bold expression.
From manual edit-mode to grid-tap UI — the case for visual cron builders
In 2026 a backend developer wiring up a Kubernetes CronJob to ping a webhook every weekday at 09:15 in Mumbai time needs to translate her intent into "15 9 * * 1-5" — no errors, no off-by-one. Doing it from memory is a Stack Overflow round-trip. Doing it on a grid is ten seconds. That delta is the entire reason this generator exists.
cron syntax has barely changed since Paul Vixie's 1987 V-3 release on comp.sources.unix. The five-field form (minute, hour, dom, month, dow) was already standard in 4.3BSD; Vixie added named months, day names, ranges, lists, steps, and the @aliases (@yearly, @monthly, @weekly, @daily, @hourly, @reboot). Every subsequent cron — ISC, fcron, dcron, GNU mcron — copied the syntax.
Quartz Scheduler (2001, by Software AG) added a 6th field for seconds, plus L (last), W (weekday-nearest), and # (nth-of-month). Spring inherited Quartz semantics. AWS EventBridge cron uses 6 fields plus a mandatory year — "cron(0 9 ? * MON-FRI *)". Kubernetes CronJob (1.4, 2016) uses bare Vixie 5-field syntax, ignoring Quartz extensions.
The hardest part of cron is the OR semantics between dom and dow. "0 9 1 * 1" in Vixie means "first of the month OR every Monday at 09:00", which surprises users coming from Quartz (where you'd use "0 9 1 * ?" to disable dow). This generator emits Vixie semantics by default — pair with our cron parser to double-check.
Daylight saving is the second hardest. A cron of "30 2 * * *" in America/New_York simply doesn't fire on the spring-forward Sunday — 02:30 EST is skipped. On fall-back the same expression fires twice. systemd timers (2014) introduced OnCalendar= with explicit monotonic semantics; k8s recommends UTC for CronJob spec.
The architectural pattern: schedule in UTC, display in local, document the IANA zone alongside the expression. This generator emits cron strings in zone-agnostic form — pair them with TZ=UTC in your cron environment.
The summary: cron is forty years old, still everywhere, and still hard to write by hand. A grid-tap UI shaves the mental overhead by an order of magnitude. This tool is that grid.
Trusted by backend, SRE, DBA and scheduling teams
“Click the grid, get a cron — exactly what every junior on my team needs. The preview of next fires seals it.”
“Generating quarterly schedules used to mean Stack Overflow. Now it's a 30-second grid tap.”
“I built ten Jenkins jobs in an afternoon thanks to the preset library. The 'every 15 min' shortcut is gold.”
“Pairing this with the cron parser gives me confidence I'm not deploying a bad schedule. Both tools open in two tabs.”
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