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About this tool
Preview upcoming run times for standard five-field cron expressions.
A crontab evaluator parses a five-field cron expression — minute, hour, day-of-month, month, day-of-week — and lists the exact wall-clock times it will fire next. It implements the crontab(5) rules used by Vixie cron and cronie, including ranges, steps, name aliases such as MON and JAN, the @daily family of macros, and the rule that a day matches if either day field matches when both are restricted. It is for anyone shipping a scheduled job who wants to confirm the schedule before it runs in production.
Open Crontab Evaluator on AltFTool — it loads instantly in your browser.
Type a five-field expression into the Cron expression box — minute, hour, day-of-month, month, day-of-week — or press one of the Common schedules buttons such as '09:30 on weekdays' or '@daily macro'. There is no run button: everything recalculates as you type, and an invalid field is called out in an alert naming the field, such as 'Minute: values must be between 0 and 59.'
Set Count from to the moment you want to measure from, which starts at your current local time, and Occurrences to show for how many runs to list — any whole number from 1 to 50, defaulting to 8.
Read Next run at the top for the weekday, time and how long the wait is, check the In plain English, Shortest gap between runs and Runs per day rows underneath, then use Copy runs to put the whole schedule on your clipboard or Reset to return to 30 9 * * 1-5 from now.
Shows the next occurrences with weekday and date, not just a description of the pattern.
Implements the OR rule that catches most people out when day-of-month and day-of-week are both set.
Impossible date and month combinations return a clear message instead of an empty table.
Minute (0-59), hour (0-23), day of month (1-31), month (1-12 or JAN-DEC) and day of week (0-7 or SUN-SAT, where both 0 and 7 mean Sunday). So 30 9 * * 1-5 means 09:30, Monday to Friday. A sixth leading field for seconds exists in Quartz and some libraries, but not in standard Unix cron.
Cron fires when EITHER field matches, not both. 0 0 1 * 1 runs at midnight on the 1st of every month AND on every Monday. This OR behaviour only applies when both fields are restricted — if one is *, only the other is consulted. It is documented in crontab(5) and is the single most common cron misunderstanding.
No. Step values are counted from the start of the field's range, not from any start time, so */5 fires at minute 0, 5, 10 … 55 of every hour. That also means a step that does not divide the range evenly resets at the boundary: */7 fires at minutes 0, 7, 14, 21, 28, 35, 42, 49, 56 — and then again at 0, only 4 minutes later.
@yearly and @annually (0 0 1 1 *), @monthly (0 0 1 * *), @weekly (0 0 * * 0), @daily and @midnight (0 0 * * *), and @hourly (0 * * * *). @reboot exists in cron but has no fixed time, so it cannot be previewed here.