YUCTS Tools

Cron Expression Explainer & Next Run Times (Standard cron / Cloudflare)

Explains each of the five cron fields in plain English and lists the next run times, keeping standard cron (server time zone) and Cloudflare Workers Cron Triggers (UTC) apart.

  • Runs in your browser with cited reference data
Which cron?

Five fields separated by spaces: minute, hour, day of month, month, day of week.

Standard cron uses the local time of the machine it runs on (usually set by /etc/localtime; some implementations support CRON_TZ).

Runs after this date and time are listed. Counting from the current time.

Result

What each field means

Minute 30
minute 30
Hour 9
hour 9
Day of month *
every day
Month *
every month
Day of week 1-5
Monday through Friday

In standard cron, weekday numbers are 0 = Sunday … 6 = Saturday (7 is also Sunday).

Next runs

Calculated in Coordinated Universal Time (UTC)

Reading the current time…

How to use

  1. Choose standard cron or Cloudflare Workers Cron Triggers.
  2. Type a cron expression (minute hour day month weekday) or press an example.
  3. For standard cron, pick the server time zone (Cloudflare always uses UTC). The meaning of each field and the next runs appear, optionally shown in another time zone too.

FAQ

How does Cloudflare differ from standard cron?

Weekday numbers differ (standard cron: 0 = Sunday; Cloudflare: 1 = Sunday). Cloudflare supports extensions such as L, W and # and always runs on UTC time, while standard cron uses the server’s local time.

What if both the day of month and the day of week are set?

In standard (Vixie) cron, when neither field starts with "*", the job runs on days matching either one. Cloudflare’s documentation does not cover this case, so the tool does not calculate run times for it.

What about daylight saving time?

If the server time zone observes DST, runs at skipped or repeated local times are marked. Debian’s cron and cronie behave differently, and both behaviours are explained.

Notes & limitations

  • What you enter is processed only on this page and is not sent to YUCTS servers.
  • Only the five-field format is supported. Formats with seconds or years (Quartz, Spring), systemd timers, Kubernetes and GitHub Actions are out of scope.
  • Standard cron follows the Vixie cron, cronie and POSIX documentation. Other implementations (such as BusyBox) or settings may behave differently.
  • Cloudflare behaviour is based on its official documentation as of the date listed under Sources. Syntax not described there is not interpreted.
  • Actual run times can be a few minutes late because of server load or configuration changes still propagating.

Data sources