★ Cron cheat sheet
Cron Expression: Every 15th of the Month
Mid-month jobs: invoices, payroll prep, usage resets.
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The expression
0 0 15 * *
At 00:00 on day-of-month 15.
- 0Minute
- 0Hour
- 15Day of month
- *Month
- *Day of week
✓ Valid 5-field cron
Quick picks
Typing by hand. Pick a pattern above to build one with inputs instead.
In plain English
At 00:00 on day-of-month 15.
Next 10 runs
Paste it into your platform
Time zone: UTC
0 0 15 * * /usr/local/bin/my-job >> /var/log/my-job.log 2>&1
- OKRuns in the server’s local time zone. cronie (RHEL, Fedora) accepts a CRON_TZ= line above the job; Debian’s cron does not.
- Heads-upEscape % as \% in the command: an unescaped % ends the command and starts stdin.
- Heads-upcron runs with a minimal PATH and no login shell. Use absolute paths and redirect output, or failures disappear.
- Linux crontab docs ↗
Cron jobs failing silently?
I build background job systems with retries, alerting and dashboards, so you hear about failures before your customers do.
01
What 0 0 15 * * means
Field by field:
| Field | Value | Matches |
|---|---|---|
| Minute | 0 | 0 |
| Hour | 0 | 0 |
| Day of month | 15 | 15 |
| Month | * | any |
| Day of week | * | any |
02
Gotchas
- Leave the day-of-week field as *. If you also set a weekday, standard cron runs on the 15th OR that weekday, not both.
- Every month has a 15th, so unlike day 31 this never skips a month.
03
Does it run everywhere?
Checked against each platform's rules, assuming UTC:
| Platform | Verdict | Why |
|---|---|---|
| Linux crontab | Works, with a catch | Escape % as \% in the command: an unescaped % ends the command and starts stdin. |
| GitHub Actions | Works, with a catch | Runs at minute 0 are the most likely to be delayed or dropped under load. GitHub suggests another minute, e.g. 17. |
| Vercel | Works, with a catch | Vercel now labels Cron Jobs “legacy” in favour of Vercel Schedules, which add time zones. Existing crons keep working. |
| AWS EventBridge | Works | Six fields: the year is added at the end, and one of day-of-month / day-of-week must be ?. |
| Kubernetes | Works, with a catch | Without timeZone, the schedule uses the kube-controller-manager’s local zone. TZ= or CRON_TZ= inside schedule is rejected from v1.29. |
04
Questions engineers actually ask
What is the cron for the 15th of every month?
0 0 15 * * runs at midnight on the 15th.
How do I run on the 1st and 15th?
List both days: 0 0 1,15 * *.
Why does my job run on days I didn't expect?
Probably the day-of-month / day-of-week OR rule. If both fields are set, cron runs when either matches. Set one of them to * to get the usual AND behaviour.
What time zone does cron use?
Whatever the scheduler uses: the server's zone for Linux cron, UTC for Vercel and EventBridge rules, UTC by default on GitHub Actions (with an optional timezone key) and the controller's zone on Kubernetes unless spec.timeZone is set.
05
Other schedules
- Every Minute
* * * * * - Every 2 Minutes
*/2 * * * * - Every 5 Minutes
*/5 * * * * - Every 10 Minutes
*/10 * * * * - Every 15 Minutes
*/15 * * * * - Every 30 Minutes
*/30 * * * * - Every Hour
0 * * * * - Every 2 Hours
0 */2 * * * - Every 3 Hours
0 */3 * * * - Every 6 Hours
0 */6 * * * - Every 12 Hours
0 */12 * * * - Twice a Day
0 9,21 * * * - Every Day at Midnight
0 0 * * * - Every Day at 9am
0 9 * * * - Every Day at Noon
0 12 * * * - Every Weekday
0 0 * * 1-5 - Every Weekday at 9am
0 9 * * 1-5 - Every Weekend
0 0 * * 6,0 - Every Monday
0 0 * * 1 - Every Friday at 5pm
0 17 * * 5 - Every Sunday at Midnight
0 0 * * 0 - Every Week
0 0 * * 0 - First Day of the Month
0 0 1 * * - Last Day of the Month
0 0 28-31 * * - Every Month
0 0 1 * * - Every Quarter
0 0 1 1,4,7,10 * - Every Year
0 0 1 1 * - Every Hour During Business Hours
0 9-17 * * 1-5 - Every 30 Minutes During Business Hours
*/30 9-17 * * 1-5
Or build your own in the cron expression builder.
06
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Fine print
Tools: on the house.
Engineer: by the hour.
Infra that doesn't page you at 3am costs a little more. I build background job systems with retries, alerting and dashboards.
I'm Himanshu, an AI and full-stack engineer. I build MVPs, AI agents and the growth plumbing around them for early-stage startups.