Is */15 the same as 0,15,30,45?

Yes, in the minute field they match the exact same four minutes. Use whichever reads better in your crontab; there is no behavioral difference in standard cron.

How do I run every 15 minutes during business hours only?

Combine the step with an hour range and weekday range: */15 9-17 * * 1-5. That fires at the quarter marks from 09:00 through 17:45, Monday to Friday, and skips nights and weekends entirely.

Can I do every 15 minutes starting from minute 7?

Yes, list the minutes explicitly: 7,22,37,52 * * * *. Some cron builds also accept the range-step form 7-59/15, which expands to the same four minutes, but the explicit list is portable everywhere.

Cron: Every 15 Minutes

The cron expression for "every 15 minutes", what each field means, and the next run times on your clock.

What is the cron expression for every 15 minutes?

The expression is */15 * * * *. Field one, */15, matches minutes 0, 15, 30, and 45; the other four fields are wildcards for hour, day of month, month, and day of week. That yields 96 runs per day, a common cadence for incremental syncs and certificate expiry checks.

*/15 * * * *

Every 15 minutes

Next 5 runs (your timezone)

Open the full Cron Expression Generator →

*/15 versus a bare 15

These two expressions look near-identical and behave completely differently. */15 * * * * steps through the minute field and fires four times an hour, at the quarter marks. 15 * * * * pins the minute to the literal value 15 and fires once an hour, at quarter past. Teams discover this when a sync that should have a 15 minute freshness window quietly delivers data up to an hour stale.

The reverse mistake also happens: someone wants quarter past each hour and writes the step form, quadrupling the run count. Reading the expression aloud helps. A leading */ always means an interval; a bare number always means a specific point on the clock.

Stagger the quarter-hour stampede

Quarter-hour marks are the busiest instants in most crontab estates. When dozens of jobs across dozens of hosts all key on minutes 0, 15, 30, and 45, shared databases and rate-limited APIs absorb synchronized bursts four times an hour. The cheapest mitigation costs nothing: keep the interval, shift the phase. 7,22,37,52 * * * * preserves an exact 15 minute cadence while landing between everyone else's runs.

Pick a different offset per service, or derive one from a hash of the hostname, and the estate's load flattens out. The technique matters most for jobs that fan out, such as a checker that probes every endpoint in an inventory on each tick.

Frequently asked

Is */15 the same as 0,15,30,45?: Yes, in the minute field they match the exact same four minutes. Use whichever reads better in your crontab; there is no behavioral difference in standard cron.
How do I run every 15 minutes during business hours only?: Combine the step with an hour range and weekday range: */15 9-17 * * 1-5. That fires at the quarter marks from 09:00 through 17:45, Monday to Friday, and skips nights and weekends entirely.
Can I do every 15 minutes starting from minute 7?: Yes, list the minutes explicitly: 7,22,37,52 * * * *. Some cron builds also accept the range-step form 7-59/15, which expands to the same four minutes, but the explicit list is portable everywhere.

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