Cron Expression Builder
Build cron expressions visually with dropdowns. Preview the next execution times and copy the expression for your server tasks, backup schedules, and automated scripts.
Quick Presets
Build Expression
Cron Expression
Next 5 Executions
Cron Field Reference
| Field | Range | Special |
|---|---|---|
| Minute | 0-59 | * , - / |
| Hour | 0-23 | * , - / |
| Day of Month | 1-31 | * , - / |
| Month | 1-12 | * , - / |
| Day of Week | 0-6 (Sun=0) | * , - / |
Embed This Tool
Put the cron expression builder on your own site or server wiki.
<iframe src="https://tools.astroworldmc.com/embed/cron-expression-builder" width="700" height="650" frameborder="0" style="border:none;border-radius:12px;" loading="lazy" title="Cron Expression Builder"></iframe>
How to write a cron expression
Start from a preset
The presets cover every minute through to once a year, and every one of them can be edited afterwards.
Set the five fields
Minute, hour, day of month, month and day of week each take a single value, a list or a step.
Check the next runs
The next five execution times are printed, which is what catches a day of month and day of week clash before it bites.
Copy the line
The expression goes straight into a crontab, a restart script or a backup job.
How It Works
Build cron expressions for server task schedulers.
The crontab format your own host runsPage updated
How to Use the Cron Expression Builder
Use the dropdown menus to select values for each of the five cron fields: minute, hour, day of month, month, and day of week. The resulting cron expression updates in real time as you make changes. Quick presets at the top let you jump to common schedules like "every hour" or "daily at midnight" with a single click.
The tool shows the next 5 execution times based on your current local time zone, so you can verify the schedule works as expected before copying it into your configuration. The human-readable description below the expression explains exactly when it will run. A nightly restart is only worth scheduling if the server comes back up, so once the next 5 run times look right, point the server status checker at the address.
Common Use Cases
Minecraft server administrators use cron expressions for automated backups, scheduled restarts, broadcast messages, and maintenance tasks. Many server management panels like Pterodactyl, AMP, and McMyAdmin support cron-based scheduling for these operations.
Plugin developers also use cron expressions in configuration files. Plugins like EssentialsX, CMI, and custom scheduler plugins accept cron syntax for scheduling automated tasks like clearing entity lag, running garbage collection, or rotating log files.
Beyond Minecraft, cron expressions are used in Linux crontab, Docker, Kubernetes CronJobs, CI/CD pipelines, and cloud services like AWS CloudWatch Events and GitHub Actions. The five-field format this tool generates is the most widely supported standard.
The special characters * (every), / (step), - (range), and , (list) can be combined for complex schedules. For example, */5 means "every 5 units" and 1-5 means "from 1 through 5". This builder covers the most common patterns through its dropdown interface while keeping the full expression visible for manual editing. Most of these schedules exist because a server slows down over a day, and the tick rate monitor turns a millisecond figure into the TPS that decides how often a restart is worth it, while the settings a restart picks up are written by the server.properties generator.
How a cron line is read
| Five fields | Minute, hour, day of month, month, day of week. This is the form crontab and most Linux schedulers expect. |
|---|---|
| Six fields | Some schedulers put seconds in front of that. Feeding a six field line to a five field scheduler shifts every value one place and schedules nonsense. |
| Star | Every value of that field. A star in the minute field means every minute of every hour the other fields allow. |
| Slash | A step. Written after a star or a range it means every nth value, so a step of 15 in the minute field fires four times an hour. |
| Comma and dash | A list and a range. They combine, so a field can hold specific values and a span at the same time. |
| Day of month against day of week | When both are set to something other than a star, the classic cron treats them as either one, not both. That is the single most common surprise in a cron line, and the list of upcoming runs on this page follows the same rule. |
Minecraft plays no part here. The order of the five fields and the meaning of the star, the slash, the comma and the dash follow the crontab format your own host runs, and the next run times are worked out in your browser against your clock.
Counting what a line actually costs you
Five fields look small until you count them. The pickers on this page hold 61 minute values, 25 hour values, 32 day values, 13 month values and 8 weekday values, and every combination is a legal line.
61 x 25 x 32 x 13 x 8 = 5,075,200 lines the five pickers can writeruns a year = 525,600 divided by the gap in minuteswhen day of month and day of week are both set, runs = the one plus the other minus the days they shareThe third sum is where schedules go wrong. Both fields restricted means or, never and, and the preview on this page lists the next runs by the same rule so you can see it before it happens on your server.
Frequently Asked Questions
Questions about cron
Why does my job fire on days I did not ask for?
Because day of month and day of week were both filled in. Classic cron runs the job when either matches, so setting the 1st and Monday gives you every 1st plus every Monday, and that is what the list above shows.
Which timezone does a cron line use?
The one the machine running it is set to, not yours and not your players'. A restart set for 04:00 fires at 04:00 server time, which is why a host in another region drifts from what you expected.
How do I run something every 10 minutes?
Use a step in the minute field. That fires at minute 0, 10, 20, 30, 40 and 50 of every hour, which is not the same as every 10 minutes counted from when you saved it.
What happens if a run takes longer than the interval?
Cron starts the next one anyway. Two backups writing at once is a normal way to corrupt a world, so a long job needs its own lock rather than a tighter schedule.
