What */3 * * * * does
The */3 in the minute field is a step value. It means 'starting at minute 0, then every 3 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, :03, :06, :09, :12, :15 ..., giving 20 runs per hour and 480 per day.
The mistake people make
Dropping the */ changes the meaning completely. 3 * * * * runs once an hour, at minute 3 — not every 3 minutes. The slash is what turns a value into an interval.
Every 3 minutes divides evenly into 60, so the schedule stays aligned to the top of each hour.
Frequently asked questions
What is the cron expression for every 3 minutes?
*/3 * * * *. The */3 step in the minute field fires the job every 3 minutes, starting at minute 0 of each hour.
How many times does */3 * * * * run per day?
480 times — 20 per hour, 24 hours a day.
Related cron expressions
Browse the full cron expression reference, or build your own expression from scratch.