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Cron Expressions — The Complete Guide with Visual Builder

2 min readZeroKit Team

Learn cron syntax, build cron expressions visually, preview next run times, and avoid timezone mistakes across GitHub Actions, Vercel, and cloud jobs.

Cron schedules power backups, queues, billing jobs, and cleaner scripts. The classic five-field Unix cron string looks cryptic until you learn the map.

Cron expression builder guide

The five fields

* * * * *
| | | | └ day of week (0–7, 0/7 = Sunday on many systems)
| | | └── month (1–12)
| | └── day of month (1–31)
| └── hour (0–23)
└──── minute (0–59)

Special characters

CharMeaningExample
*every value* * * * * every minute
,list0 8,12,18 * * *
-range0 9-17 * * * hourly during work hours
/step*/15 * * * * every 15 minutes

Patterns you will copy-paste

ScheduleExpression
Hourly at :000 * * * *
Daily midnight0 0 * * *
Weekdays 08:3030 8 * * 1-5
Every 6 hours0 */6 * * *

Build visually → ZeroKit Cron Builder previews next run times in plain language.

Platforms differ slightly

PlatformGotcha
GitHub ActionsUTC only in schedule
Vercel cronsUTC, declarative in config
Some AWS rulesmay use six fields (seconds)

Cron expressions people search for

NeedCron expression
Every 5 minutes*/5 * * * *
Every day at 9 AM0 9 * * *
Every Monday morning0 9 * * 1
First day of every month0 0 1 * *
Weekdays at 6 PM0 18 * * 1-5

FAQ

Timezone?

Assume UTC on most cloud schedulers unless the product documents otherwise.

Sub-minute?

Classic cron's smallest step is one minute. Sub-minute needs another system.