★ Cron cheat sheet
Cron Expression: Every 15 Minutes
Quarter-hourly: :00, :15, :30, :45. Common for report refreshes, cache warming and metrics roll-ups.
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The expression
*/15 * * * *
Every 15 minutes.
- */15Minute
- *Hour
- *Day 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
Every 15 minutes.
Next 10 runs
Paste it into your platform
Time zone: UTC
*/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 */15 * * * * means
Field by field:
| Field | Value | Matches |
|---|---|---|
| Minute | */15 | 0, 15, 30, 45 |
| Hour | * | any |
| Day of month | * | any |
| Month | * | any |
| Day of week | * | any |
02
Gotchas
- Equivalent to 0,15,30,45 * * * *. The list form is easier to shift if you need to stagger, e.g. 7,22,37,52.
- Fine on GitHub Actions; not allowed on Vercel Hobby.
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 | Not supported | Hobby plan: deploy fails, because Hobby cron jobs may run at most once per day. Pro and Enterprise allow once per minute. |
| 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 expression for every 15 minutes?
*/15 * * * *, which fires at minutes 0, 15, 30 and 45 of every hour.
Why does my 15-minute job run at odd times on GitHub?
GitHub Actions schedules are best-effort and can be delayed during high load, especially near the top of the hour.
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 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 - Every 15th of the Month
0 0 15 * * - 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.