What is the cron expression for every 3 days?

Use 0 0 */3 * * (standard five-field cron). Verify the next run times in the free cron debugger before you deploy.

Can Crontap run this schedule?

Cron counts days of the month, so `0 0 */3 * *` restarts on the 1st and the gap at a month boundary can be shorter than 3 days. A single standard 5-field cron cannot preserve exact rolling 3-day spacing across month boundaries. For a predictable approximation, use fixed weekdays such as Monday and Thursday (`0 0 * * 1,4`), which produces 3/4-day gaps each week.

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Cron recipe

Cron job every 3 days: the exact expression

The expression

five-field cron

0 0 */3 * *

Paste it into crontab -e, your platform cron config, or tool.crontap.com/cronjob-debugger to preview the next runs.

What it does

Runs at midnight on days 1, 4, 7, … 31 of each month. The `*/3` step is evaluated inside the day-of-month field and restarts when a new month begins; it is not a continuous 72-hour interval.

When to use it

Billing and dunning follow-ups
Retry failed payments or advance an account-recovery workflow on a three-day calendar cadence.
ERP and inventory reconciliation
Compare slower-moving operational data without running a full sync every night.

Common variations

0 9 */3 * *
The same stepped calendar days at 9:00am instead of midnight.

Run this with Crontap

External HTTP cron hits your URL on this schedule, records every run, and emails you when a run fails. No daemon on the box, no drift when the server reboots. Pro schedules down to a 1-minute cadence, from $2.99/mo and scaling as you grow.

Schedule this interval Preview in the cron debugger →

Related recipes

More patterns in the cron syntax cheat sheet and what is a cron job in Linux.

FAQ

What is the cron expression for every 3 days?: Use 0 0 */3 * * (standard five-field cron). Verify the next run times in the free cron debugger before you deploy.
Can Crontap run this schedule?: Cron counts days of the month, so `0 0 */3 * *` restarts on the 1st and the gap at a month boundary can be shorter than 3 days. A single standard 5-field cron cannot preserve exact rolling 3-day spacing across month boundaries. For a predictable approximation, use fixed weekdays such as Monday and Thursday (`0 0 * * 1,4`), which produces 3/4-day gaps each week.