HTTPfy

Every 3 hours

At 00:00, 03:00, 06:00, ... 21:00 every day: 8 runs a day.

0 */3 * * * Open in Crontab Generator
2,920runs in the next 365 days
56runs per week
3 hoursbetween every run
03:00next run, Wed 11 Nov UTC

What it is used for

Medium-frequency imports, price or inventory syncs and backups of active databases.

Field by field

FieldValueMatches
Minute00
Hour*/30, 3, 6, 9, 12, 15, 18, 21
Day of month*every value
Month*every value
Day of week*every value
 
0 */3 * * * /path/to/job

Next 10 run times

Computed when this page loaded (2026-11-11 02:24 UTC), assuming the scheduler runs in UTC.

#UTCYour local time
1Wed 2026-11-11 03:00
2Wed 2026-11-11 06:00
3Wed 2026-11-11 09:00
4Wed 2026-11-11 12:00
5Wed 2026-11-11 15:00
6Wed 2026-11-11 18:00
7Wed 2026-11-11 21:00
8Thu 2026-11-12 00:00
9Thu 2026-11-12 03:00
10Thu 2026-11-12 06:00

Things to watch with this schedule

  • 3 divides 24, so the gap is always exactly 3 hours, including across midnight.

Kubernetes CronJob

Kubernetes uses the same five fields. Set spec.timeZone (stable since Kubernetes 1.27), otherwise the schedule follows the time zone of kube-controller-manager.

apiVersion: batch/v1
kind: CronJob
metadata:
  name: every-3-hours
spec:
  schedule: "0 */3 * * *"
  timeZone: "Etc/UTC"
  concurrencyPolicy: Forbid
  startingDeadlineSeconds: 300
  jobTemplate:
    spec:
      template:
        spec:
          restartPolicy: OnFailure
          containers:
            - name: job
              image: debian:bookworm-slim
              command: ["/bin/sh", "-c", "/app/run-job.sh"]

GitHub Actions

Workflow schedules use five-field cron in UTC and run only from the default branch. Runs at minute 0 are the most likely to be delayed or dropped when GitHub is busy; an odd minute such as 7 or 23 starts more reliably.

on:
  schedule:
    - cron: '0 */3 * * *'   # UTC

jobs:
  run:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - run: ./run-job.sh

systemd timer

The equivalent OnCalendar= value is *-*-* 00/3:00:00. Check it with systemd-analyze calendar '*-*-* 00/3:00:00', which prints the next elapse time. Persistent=true runs a missed job after downtime, which classic cron never does.

[Unit]
Description=Every 3 hours

[Timer]
OnCalendar=*-*-* 00/3:00:00
Persistent=true

[Install]
WantedBy=timers.target

AWS EventBridge

EventBridge rules take six fields (minute, hour, day-of-month, month, day-of-week, year) in UTC; EventBridge Scheduler can use a time zone. One of day-of-month and day-of-week must be ?, and day-of-week runs 1-7 from Sunday, so names are used here.

cron(0 0/3 * * ? *)

Quartz Scheduler (Java)

Quartz adds a leading seconds field and needs ? in either day field; days of the week are 1 (SUN) to 7 (SAT).

0 0 0/3 * * ?

Spring's @Scheduled(cron = ...) also uses six fields, but numbers days of the week 0-7 with Sunday as 0 or 7, like Unix cron; the names shown above work in both.

Related schedules