Cron Every Night at 11pm

0 23 * * *

At 23:00

Field by Field

Field	Value	Matches
Minute	0	0
Hour	23	23
Day of month	*	every day
Month	*	every month
Day of week	*	every day

23 Is 11pm

The hour field is 0–23 with no am or pm, so 11pm is 23. Writing 11 gives you 11 in the morning, which is a mistake that survives review surprisingly often because 0 11 * * * looks plausible.

The Date Boundary

An 11pm job runs on the same calendar day it reports on, which sounds convenient and creates a specific trap: if the job runs long, or the server is in a time zone an hour ahead of the data, it can cross midnight and attribute results to the wrong day.

Compute the reporting date once at the start of the run and pass it explicitly, rather than calling date repeatedly inside the job. A job that asks the clock twice can get two different answers.

Late Evening Is Genuinely Quiet

For consumer products, 23:00 local is past the evening peak and before the overnight batch window. It is a good slot for work that needs low contention but must not wait until morning.

Time Zones

Standard crontab evaluates in system local time. Vercel Cron, GitHub Actions, Kubernetes CronJobs and AWS EventBridge all evaluate in UTC. If converting your local time crosses midnight, the day-of-week field shifts too — weekdays at 5pm in UTC-07:00 is 0 0 * * 2-6, not 0 0 * * 1-5.

The Day-Field Trap

When both the day-of-month and day-of-week fields are restricted, cron matches either, not both. 0 0 13 * 5 runs on every 13th *and* every Friday — not Friday the 13th. Leave one of them as * unless you genuinely want the union.

Other Common Schedules

Expression	Runs
* * * * *	Every minute
*/5 * * * *	Every 5 minutes
*/15 * * * *	Every 15 minutes
0 * * * *	Every hour, on the hour
0 0 * * *	Every day at midnight
0 9 * * *	Every day at 9am
0 9 * * 1-5	Weekdays at 9am
0 9 * * 1	Every Monday at 9am

Making the Job Safe

• Assume double firing. DST transitions, restarts and retries all cause it. Make the job

idempotent rather than assuming exactly-once.

• Assume overlap. Cron starts the next run whether or not the last one finished. Take a

lock.

• Avoid :00. Every hourly job on the internet fires at the top of the hour; a random

minute spreads load on shared APIs.

• Log the start and end. A cron job that silently stops running is invisible until

someone notices the missing output.