build a schedule

frequency minute

builds 30 9 * * *

How to read a cron expression

A cron expression is five fields separated by spaces: minute hour day-of-month month day-of-week. Each field says which values match, and a job runs whenever the current time matches every field at once.

The patterns are the same in every field. A star (*) matches every value. A list like 1,15,30 matches those exact values. A range like 9-17 matches everything from 9 to 17. A step like */15 matches every 15th value from the field minimum, so */15 in the minute field fires at :00, :15, :30, and :45. You can combine them: 0-30/10 means 0, 10, 20, 30.

Two fields accept names. Months take JAN through DEC, and weekdays take SUN through SAT, so 0 9 * * MON-FRI reads as 9am on weekdays. Sunday is both 0 and 7. The shortcuts @hourly, @daily, @weekly, @monthly, and @yearly expand to the full five-field form.

Common cron examples

*/15 9-17 * * 1-5 runs every 15 minutes from 9am to 5pm, Monday to Friday.
0 0 * * 0 runs at midnight every Sunday.
30 2 1 * * runs at 2:30am on the first of every month.
0 */6 * * * runs every six hours.

Paste any of these into the box above to see the plain-English reading and the next five run times.

FAQ

What does */15 mean in cron?: It is a step: every 15th value starting from the field minimum. In the minute field that is :00, :15, :30, and :45. In the hour field */6 would mean 0, 6, 12, and 18.
Does Cronlet use local time or UTC?: The run times on this page use your browser's local time zone, the same way a crontab uses the machine's local time. There is no server involved.
Why do day-of-month and day-of-week act strangely together?: In standard cron, when both day fields are restricted a day matches if either one matches, not both. So 0 0 13 * 5 fires on the 13th and on every Friday, not only Friday the 13th. Cronlet follows this rule and writes "or" in the description to make it visible.
Can I turn plain English back into a cron string?: Yes. The builder under the translator lets you pick a frequency and time, and it writes the matching expression into the box for you.
Is Cronlet free to use?: Yes. It is MIT licensed with no runtime dependencies. The same parser that powers this page ships as a small TypeScript library you can install from npm.