Cron every 20 minutes

Yes. It fires at :00, :20, and :40, so all three gaps—including :40 to the next :00—are exactly 20 minutes. It never selects :10, :30, or :50. Expression: */20 * * * *

Use 5-59/20 * * * *. It fires at :05, :25, and :45 in every hour. Expression: 5-59/20 * * * *

Use */20 9-17 * * 1-5. It fires at :00, :20, and :40 in each included hour, including the 17:00 hour. Expression: */20 9-17 * * 1-5

Use 10-59/20 * * * *. The range starts the 20-minute step at :10, producing :10, :30, and :50 in each hour. Expression: 10-59/20 * * * *

A change can wait almost 20 minutes before pickup, plus scheduler and execution delay. The cadence runs 72 times daily, compared with 48 for every 30 minutes.

Use */20 * * * 1-5. The schedule keeps its :00/:20/:40 alignment from Monday through Friday and pauses on weekends. Expression: */20 * * * 1-5

The scheduler decides. Vixie/cronie can skip or double :00/:20/:40 local matches; GitHub advances nonexistent local times; EventBridge Scheduler skips spring and runs once in the fall overlap. UTC-only Vercel and Cloudflare are unaffected.

Yes. Twenty minutes is above GitHub Actions' five-minute minimum and EventBridge's one-minute minimum.

Use cron(0/20 * * * ? *). EventBridge uses six fields including year, requires ? in one day field, and wraps them in cron(...). Expression: 0/20 * * * ? *

Use 0 0/20 * * * ?. The leading zero is the seconds field, and the minute step selects :00, :20, and :40. Expression: 0 0/20 * * * ?

This cadence makes 72 calls per day, so account for API quotas, execution cost, and retry traffic. Crontap can run the schedule with retries for failed HTTP calls.

*/20 * * * *. Paste this into Linux crontab, Vercel cron, node-cron, robfig/cron, or a Kubernetes CronJob to run a job every 20 minutes; AWS EventBridge and Quartz need the six-field form.

The editor above shows the next 30+ runs on a calendar in your local timezone, plus a plain-English description. If the calendar matches your intent, the cron is correct.

Linux crontab, Vercel cron jobs, node-cron, robfig/cron, and Kubernetes CronJob accept the five-field form as is. AWS EventBridge and Quartz use six-field expressions with a ? in one of the day fields; see the AWS and Quartz guides for the conversion. Vercel's free Hobby plan caps the minimum frequency at once-per-day; the Pro plan removes that cap.

Most schedulers will start the new run anyway, leading to overlap. To prevent this, wrap the command with flock -n /tmp/myjob.lock /path/to/script.sh on Linux, or set concurrencyPolicy: Forbid on Kubernetes CronJob. Vercel and EventBridge may overlap runs if the previous one is still executing; make the handler idempotent.