Cron Expression for Every 12 Hours
0 */12 * * *0 */12 * * * runs twice a day, at 00:00 and 12:00. It is exactly equivalent to 0 0,12 * * *, which many people find easier to read.
Next runs, in your timezone
Twice a day, twelve hours apart
With a 24-hour field, a step of 12 yields hours 0 and 12 — nothing else. If you want the two runs at, say, 09:00 and 21:00 instead, the list form is the natural spelling.
0 */12 * * * # 00:00 and 12:00
0 9,21 * * * # 09:00 and 21:00 — same twice-daily cadenceEquivalent expressions
0 0,12 * * *— identical schedule, spelled as a list0 9,21 * * *— twice daily at 09:00 and 21:00
Run a SQL query on this schedule
If the job behind this schedule is a database query, you can skip the server and the crontab: SaturnSQL runs saved SQL queries on a cron expression — this exact syntax, with a real timezone field — and delivers the results to Google Sheets or Slack. Minimum interval 5 minutes.