*/45 * * * *
Cron reads this as: every 45th minute.
Read the run times below before using this expression. The schedule it produces is not the one most people expect.
Next 5 runs
These times are in your browser's local time zone. Cron itself uses the server's zone, which on most cloud hosts is UTC. If the difference matters here, see time zones & DST.
- Calculating…
When to use this schedule
People often use this expression expecting a 45-minute cycle. It does not produce one, and the reason is worth understanding before you use it anywhere.
What to watch out for
*/45 means "every 45th value within 0-59", which yields only :00 and :45. The gaps alternate between 45 minutes and 15 minutes, because the step resets at the top of every hour instead of continuing from the last run. Standard cron cannot express a true 45-minute cycle, since 45 does not divide 60. If you need one, you can accept a nearby interval that divides evenly (*/30 or 0 */1 * * *), write out the three-hour repeating pattern by hand across multiple lines, or use a scheduler with real interval support, such as a systemd timer with OnUnitActiveSec=45min.
The crontab line
*/45 * * * * /usr/local/bin/your-job.sh >> /var/log/your-job.log 2>&1Send the output to a log you will read. By default cron mails it, and on a host with no mail transport that mail is silently dropped. See the crontab guide for the surrounding syntax.
Related schedules
| Expression | Schedule |
|---|---|
*/30 * * * * | Every 30 minutes (divides evenly) |
0 * * * * | Every hour (divides evenly) |
0,45 1-23/3 * * * | Hand-written approximation |
Build your own
If this page doesn't cover the schedule you need, compose it field by field in the visual builder, or paste an expression you already have into the explainer for a per-field breakdown. The examples library has sixty schedules in one place, and the guides cover crontab syntax, time zones, troubleshooting and production practices.