Build cron expressions by pointing and clicking, or paste one in — with a plain-words summary and the next five run times computed against your local clock. Runs entirely in your browser — your numbers never leave this device.
Cron fields are read against the local clock of the machine running the job, and the runs above are shown in your browser's local time. One classic trap: when both the day-of-month and day-of-week fields are restricted, a day matches if either one does — this engine follows that standard rule.
| Field | Range | Operators that work in it |
|---|---|---|
| Minute | 0–59 | * , - / — e.g. */15 is every quarter hour |
| Hour | 0–23 | * , - / — e.g. 9-17 is hourly during work hours |
| Day of month | 1–31 | * , - / — e.g. 1,15 is the 1st and 15th |
| Month | 1–12 | * , - / — e.g. */3 is quarterly |
| Day of week | 0–7 (0 and 7 = Sunday) | * , - / — e.g. 1-5 is Monday to Friday |
Cron is the Unix scheduler's one-line language: five fields, and the job runs whenever the current minute matches all of them. This tool works in both directions — choose presets per field (every day at 09:00, weekdays only, the 1st and 15th) and the expression is assembled for you, or paste any 5-field expression and get it parsed back into fields, a plain-words summary for the common shapes, and the next five times it will fire. The builder and the free expression field stay in sync, so you can start from a preset and hand-tune one field without starting over.
The run times are computed against your local clock, which is how cron itself behaves on a machine — a '0 9 * * *' job fires at 09:00 in the timezone of whatever runs it. That matters when you copy an expression to a server in another timezone (most cloud servers keep UTC): the expression travels, the wall-clock meaning does not. The summary names the common patterns in words because most real schedules are one of a handful of shapes, and anything outside them is honestly labelled a custom schedule rather than force-fitted into a sentence.
One trap deserves its own paragraph because it has bitten everyone: the day rule. If both day-of-month and day-of-week are restricted, standard cron fires when EITHER matches, not both — '0 0 1 * 1' runs on the 1st of every month AND on every Monday, as the worked example shows. To get 'the first Monday of the month' you need a different mechanism entirely. This engine follows the standard rule and the example demonstrates it, dates and all.
Restrict the day-of-week field to the range 1-5 and leave day-of-month as *: 0 9 * * 1-5. The summary will read it back as a custom schedule unless it matches one of the named shapes — build it with the presets: minute 0, hour 09, day-of-week 'Weekdays (Mon–Fri)'.
The standard cron day rule: when both day-of-month and day-of-week are restricted (neither is *), the day matches if either field does. '0 0 1 * 1' therefore means the 1st of the month plus every Monday — the worked example lists exactly those dates. If you want only one condition, leave the other field as *.
Not in the standard 5-field syntax this tool builds: there is no L or # operator, and day-of-month 31 simply never fires in shorter months (a 29 February job fires only in leap years — this engine will happily find 2024-02-29 for '0 0 29 2 *'). Some schedulers add those operators as extensions; standard crontab does not have them, and scripts that need them usually check the date themselves.
Yours — the runs are computed and displayed in your browser's local time, matching how cron fires on a machine set to your timezone. If you paste the expression into a server that keeps UTC, the same expression fires at the same numbers on the UTC clock, which is a different moment. Convert deliberately when the schedule is about people, not machines.
The full range stepped by 15: 0, 15, 30, 45. Steps compose with ranges too — 9-17/2 in the hour field is 9, 11, 13, 15, 17 — and the parser view in this tool shows the expanded value list each field produces, so an expression's meaning never has to be guessed.
Yes. The day-of-week range is 0–7 with both endpoints defined as Sunday, a quirk inherited from early cron. This parser folds 7 onto 0, so '0 0 * * 7' and '0 0 * * 0' produce identical runs — convert 7s to 0s in expressions you keep, for the next reader's sake.
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