Crontab Guru — edit each cron field and see what it means

How to use Crontab Guru

1. Fill in Minute, Hour, Day of month, Month and Day of week. Each box takes one cron field, such as 5, */15, 9-17 or MON-FRI.
2. Choose the Time zone your cron daemon runs in.
3. Set Starting from to the moment you want the run list to begin. Leave it as is for now.
4. Read the plain-English Schedule, the warnings, the Fields table and the next five runs, shown in your zone, in UTC and as a distance from the start.

What it does and when to use it

When a cron job fires at the wrong time, the fault is usually one field: an hour in UTC rather than local time, a day-of-month that should have been *, or a minute left as * that makes the job run 60 times an hour. With one box per field you can change a single value and watch the meaning and the run list change. Use it to review a crontab before a deploy or to check a daylight-saving change.

To build a line from menus instead, use the Cron Generator. For 6-field expressions and macros, use the Cron Parser.

How it works

The five boxes are joined into one POSIX-style line and checked by the cron-parser library, which also steps through the next matches in the chosen time zone. The cronstrue library writes the English sentence. Two checks add warnings: a * minute field, and day-of-month and day-of-week both being restricted, which cron treats as “either one matches”. Everything runs in your browser.

Worked examples

Daily at 04:05. Fields 5 4 * * * from 2 October 2026 give Schedule: At 04:05 and one run in the next 24 hours, at 2026-10-02 04:05:00.

A London job across the clock change. 0 22 * * 1-5, time zone Europe/London, starting 23 October 2026:

1 | 2026-10-23 22:00:00 | 2026-10-23T21:00:00Z
2 | 2026-10-26 22:00:00 | 2026-10-26T22:00:00Z

The local time stays at 22:00 but the UTC time moves by an hour after British Summer Time ends on 25 October.

Last day of the month. 0 9 L * * lists 31 October through to 2027-02-28 09:00:00. Vixie cron, common on Linux, does not support L, so check your scheduler first.

A common mistake. * */6 * * * reports 240 runs in the next 24 hours and a warning: the minute field * fires every minute of hours 0, 6, 12 and 18. Use 0 */6 * * * for four runs a day.

Limits and tips

• Out-of-range values give an error such as “got value 25 expected range 0-23”.
• Times in the list come from the browser’s time zone data, not from your server. Check the server zone with date or timedatectl.
• For one-off date maths around a run, use the Unix timestamp converter.