Cron for Every 45 Minutes

The obvious-looking 0,45 * * * * does not run every 45 minutes. It runs at :00 and :45 past every hour — a 45-minute gap, then a 15-minute gap, repeating. That's because cron's minute field resets every hour; it has no memory of when the last job ran.

If you need a true, unbroken 45-minute interval regardless of the clock, cron alone can't do it — you'd need a long-running process or a scheduler with interval-based (not clock-based) semantics, such as a systemd timer with OnUnitActiveSec=45min, or a simple loop with a sleep. If a slightly uneven 45/15-minute alternating gap is actually fine for your use case, 0,45 * * * * above works as-is.

Want to build a different schedule, or check how a related expression behaves? Open this exact expression in the full Cron Expression Builder to edit it directly.