How to Read a Cron Expression: Examples and Cheat Sheet

A cron expression is a compact but not always obvious way to write a schedule: a string like */15 * * * * won't mean much until you understand the format. Cron is used in Linux (crontab), CI/CD pipelines, and many task schedulers, and a mistake in a single field can run a job at the wrong time. Let's cover the format and common examples.

The five cron fields

A classic cron expression has five fields in a strict order:

minute  hour  day of month  month  day of week
0-59    0-23      1-31        1-12      0-7

Day of week: 0 and 7 both mean Sunday, 1 is Monday, and so on through Saturday (6).

Special characters

• * — "any value" (every minute/hour/day, depending on the field).
• */N — "every N units," for example */15 in the minute field means every 15 minutes.
• a-b — a range, for example 1-5 in the day-of-week field means Monday through Friday.
• a,b,c — a list of specific values, for example 0,30 in the minute field means at minute 0 and minute 30 of every hour.

Example breakdown

A common mistake

Mixing up the day-of-month and month fields, or forgetting that day-of-week numbering starts at Sunday (0) rather than Monday — which can make a "weekdays only" schedule accidentally include a weekend day. Before saving a job, it's worth double-checking that the expression decodes to exactly what you intended.

Checking it online

Don't try to keep the field order and special characters in your head — paste the expression into the cron decoder, and it will translate it into plain English ("at 08:30, on weekdays") while also validating the syntax. Note that shorthand expressions like @daily aren't supported yet — only the classic 5-field format.