Cron Expression Builder and Explainer
Create and understand cron schedules without memorising the syntax. The Build mode turns presets and simple per-field dropdowns into a valid five-field cron expression you can copy straight into crontab. The Explain mode does the reverse: paste any expression and read a plain-language description plus the next five run times in your own timezone. Everything runs in your browser.
Quick presets
Try an example
Cron expression
* * * * *
What it means
Nothing to explain yet
Paste a 5-field cron expression to see what it means and when it runs next.
Plain-language meaning
Next 5 run times
How to use
- Open the Build tab and pick a preset such as hourly or weekly.
- Fine-tune any field (minute, hour, day, month, weekday) with the dropdowns.
- Copy the generated cron expression shown live on the right.
- Switch to Explain, paste a cron line, and read its meaning and next runs.
Features
- One-click presets: every minute, every 5 minutes, hourly, daily, weekly, monthly
- Per-field control for specific values, ranges, lists and step intervals
- Live validation against the 0-59, 0-23, 1-31, 1-12, 0-7 ranges
- Plain-language explanation of any pasted cron expression
- Next 5 run times computed in your local timezone
- 100% client-side — nothing you type is uploaded
Frequently asked questions
What is a cron expression?
A cron expression is five space-separated fields — minute, hour, day of month, month and day of week — that tell a scheduler when to run a job. For example, 0 9 * * 1-5 means 09:00 on weekdays.
Which operators are supported?
The standard four: * (every value), - for a range like 1-5, , for a list like 1,15,30, and / for step intervals like */15. Each field is validated against its allowed number range as you type.
What does 0 or 7 mean in the day-of-week field?
Both 0 and 7 represent Sunday, matching Vixie/Linux cron. So * * * * 0 and * * * * 7 both run every Sunday.
What timezone are the next run times shown in?
They are computed in your browser using your device's local timezone, which is displayed under the list. Remember that your server may run cron in UTC or a different zone.
When day-of-month and day-of-week are both set, which one wins?
Cron treats them as OR when both are restricted: the job runs when either matches. If one is *, only the other applies. This tool follows the same rule when listing run times.