Cron Expressions Explained, With Examples

The five fields

 ┌───────── minute        (0–59)
 │ ┌─────── hour          (0–23)
 │ │ ┌───── day of month  (1–31)
 │ │ │ ┌─── month         (1–12 or JAN–DEC)
 │ │ │ │ ┌─ day of week   (0–6 or SUN–SAT; 7 = Sunday too)
 │ │ │ │ │
 *  *  *  *  *   command

Quartz/Spring add a seconds field at the start, making it six. Some implementations add a year field at the end. Always confirm which dialect your scheduler uses.

The special characters

• * — any value
• , — a list: 1,15,30
• - — a range: 9-17
• / — a step: */5 means every 5
• ? — "no specific value" (Quartz only, used in day-of-month / day-of-week)
• L — last (Quartz; e.g. L in day-of-month = last day)
• # — nth weekday of month (Quartz; 6#3 = third Friday)

The gotcha that catches everyone

In standard Unix cron, day-of-month and day-of-week are OR'd, not AND'd. If you write:

0 9 1 * MON   # 9am, on the 1st of the month, OR on Monday

…it fires every Monday and on the 1st of every month. To get "9am on the 1st only if it's a Monday", you need application-level logic — pure cron can't express it.

Timezones

Linux cron uses the system timezone (often UTC on servers, local time on workstations). Managed schedulers are different:

• Kubernetes CronJob: UTC by default; spec.timeZone available since v1.27.
• AWS EventBridge: UTC. Use the cron(min hour day-of-month month day-of-week year) 6-field syntax.
• GCP Cloud Scheduler: configurable timezone per job.

Always write the timezone next to the expression in code comments. "Midnight" without a timezone is a future incident.

Reference table

The expressions you actually need:

* * * * *          every minute
*/5 * * * *        every 5 minutes
0 * * * *          top of every hour
0 */2 * * *        every 2 hours
30 9 * * *         every day at 09:30
0 9 * * 1-5        weekdays at 09:00
0 9 * * MON-FRI    (same, named form)
0 0 * * 0          every Sunday at midnight
0 0 1 * *          1st of every month at midnight
0 0 1 1 *          midnight on January 1st
15 10 * * 1        Mondays at 10:15
0 22 * * 1-5       weekdays at 22:00 (nightly job)
0 0 * * 6,0        every Saturday and Sunday at midnight
*/15 9-17 * * 1-5  every 15 min, business hours, weekdays

Common mistakes

1. Wrong field count. Pasting a 6-field Quartz expression into Linux cron silently misinterprets the meaning.
2. Forgotten timezone. A "daily report at 8am" runs at 3am for half the world.
3. DST drift. An expression like 30 2 * * * either runs twice or skips entirely on DST transitions in local-time schedulers.
4. Overlapping runs. A job that takes 6 minutes scheduled every 5 will pile up. Use a lockfile, or a scheduler with concurrencyPolicy: Forbid.
5. Step ambiguity. */7 in the hour field doesn't fire every 7 hours — it fires at hours 0, 7, 14, and 21, then jumps back to 0. Use explicit lists for non-divisors.

FAQ