Cron Expression Parser

Cron is a time-based job scheduler found in Unix-like operating systems. A cron expression is a string of five fields (minute, hour, day-of-month, month, day-of-week) that define a recurring schedule. Each field can be a single value, a comma-separated list, a range (1-5), or a step (*/15). The scheduler fires a job whenever the fields match the current wall-clock time — with one exception, below.

Day-of-month and day-of-week are ORed, not ANDed, whenever both are restricted. 0 0 13 * 5 does not mean "the 13th, but only on a Friday" — it means "the 13th or any Friday", around 64 runs a year rather than a couple. Every other pair of fields is ANDed, which is what makes this one easy to read wrongly. When either day field is * the question does not arise, and the other field simply applies.

Wildcards and steps make it easy to express common patterns: * matches every value in the field's range; */n matches every nth value starting from the minimum. For example, */5 in the minute field produces 0, 5, 10, … 55. A range with step like 0-30/10 yields 0, 10, 20, 30.

Timezone gotcha: cron runs in the server's local timezone unless the daemon is configured otherwise (e.g. via CRON_TZ or systemd's OnCalendar). This tool shows times in your browser's local timezone. When DST transitions occur, an hour may be skipped or repeated — check your platform's documentation for how it handles the ambiguity.

6-field cron puts a seconds field first, the layout Quartz and Spring use. This tool reads a 6-field expression that way, and both the plain-English reading and the run list honour the seconds: */10 * * * * * runs every 10 seconds. AWS EventBridge also has six fields but a different layout — minute first, a trailing year, and ? in one of the day fields — which this tool does not parse.

Sources

• POSIX, The Open Group Base Specifications: crontab. The five-field syntax, and the rule that when both day fields are restricted a job runs on a day matching either.
• Test oracle: npm cron-parser, cross-checked against Python croniter. Next-run lists from two independent implementations, which agree on every case in the fixture.

Link to this tool with values filled in

Everything after the # stays in your browser — it is never sent to a server — so a link like this opens the tool ready to go without the values travelling anywhere but the address bar:

https://crunchify.net/tools/cron-parser#expression=0%209%20*%20*%201-5

Join the settings with &, and percent-encode each value so that spaces, newlines and any #, &, = or % inside one do not break the link. Leave a setting out to accept its default. If a setting is not recognised, the page says so rather than quietly ignoring it.

• expression (also cron, expr, schedule or q) — text, up to 120 characters, required. The cron expression, standard five-field form (minute hour day-of-month month day-of-week). Shorthand such as @daily is accepted.
• runs (also count or next) — a whole number from 5 to 25, defaults to 5. How many upcoming run times to list.