What */45 * * * * does
The */45 in the minute field is a step value. It means 'starting at minute 0, then every 45 minutes'. The four remaining asterisks mean every hour, every day of the month, every month and every day of the week — so the job runs continuously, all year.
Within any given hour it fires at :00, :45.
Watch the hour boundary. The step operator restarts at the top of every hour, so an interval that doesn't divide evenly into 60 produces an uneven gap when the hour rolls over.
The mistake people make
Dropping the */ changes the meaning completely. 45 * * * * runs once an hour, at minute 45 — not every 45 minutes. The slash is what turns a value into an interval.
Careful: */45 does not mean 'every 45 minutes'. It fires at minute 0 and minute 45 only, then resets at the top of the next hour, so the real gap alternates between 45 and 15 minutes. There is no clean way to express a true 45-minute interval in standard cron.
Frequently asked questions
What is the cron expression for every 45 minutes?
*/45 * * * *. The */45 step in the minute field fires the job every 45 minutes, starting at minute 0 of each hour.
How many times does */45 * * * * run per day?
It runs 2 times per hour, but the spacing is uneven because 45 does not divide evenly into 60.
Related cron expressions
Browse the full cron expression reference, or build your own expression from scratch.