Cron every odd hour: the expression, explained, in GitHub Actions
The cron expression for “every odd hour” is 0 1-23/2 * * *. This page shows what each field does, the next five times it will fire, the mistake most people make with it, and a working GitHub Actions example you can paste.
The expression
| Field | Value | Meaning |
|---|---|---|
| minute | 0 | exactly 0 |
| hour | 1-23/2 | every 2 hours, from 1 to 23 |
| day of month | * | every day of month |
| month | * | every month |
| day of week | * | every day of week |
Next five runs (UTC, from now)
- 2026-09-18 01:00 UTC
- 2026-09-18 03:00 UTC
- 2026-09-18 05:00 UTC
- 2026-09-18 07:00 UTC
- 2026-09-18 09:00 UTC
Mistakes people make with this schedule
- Writing "*/2" and expecting odd hours. Steps count from 0, so "*/2" is even hours; "1-23/2" starts the step at 1 instead.
- Assuming the server clock is your clock. Cron runs in the machine’s timezone unless the runtime says otherwise; the examples here are UTC.
- No lock around a job that might overlap itself, and no alert when it silently stops. That second one is what Supercrontab is for.
Run it in your stack
# .github/workflows/cron.yml
on:
schedule:
- cron: '0 1-23/2 * * *'
jobs:
run:
runs-on: ubuntu-latest
steps:
- run: curl -fsS https://example.com/cron/runScheduled workflows can be delayed by many minutes at busy hours, and are disabled after 60 days of repo inactivity.
Questions
Does 0 1-23/2 * * * run in my local time?
Only if the scheduler is configured for it. crontab uses the system timezone; Vercel and GitHub Actions always use UTC; Laravel and node-cron take a timezone option. In Supercrontab the timezone is a field on the job.
What if the previous run is still going?
Classic cron starts the next run anyway. Add a lock (flock on Linux, withoutOverlapping() in Laravel) or let Supercrontab skip the tick while the previous request is open.
Is there a shorter way to write this?
No. The five-field form is the shortest portable version.