What happens if I set both day of month and day of week?

Cron treats them as OR, not AND — this is the single most common cron mistake. `0 0 13 * 5` does not mean “Friday the 13th”; it means midnight on the 13th of every month, and also midnight every Friday. If you need both conditions, you have to check the date inside the job itself.

Which time zone does a cron job run in?

The one the machine or the scheduler is configured with, not yours. That is the second most common surprise: a job set for 02:00 runs at 02:00 server time, and on a server set to UTC that may be the middle of your afternoon. Many schedulers let you declare a CRON_TZ or a timezone field — set it explicitly rather than assuming.

How does a step like */15 work?

It runs whenever the field divides evenly by the step, counting from the start of the range. `*/15` in the minute field fires at :00, :15, :30 and :45. Note that it counts from zero rather than from when you installed the job, so `*/7` produces an uneven gap at the top of each hour.

Cron Expression Generator

Build a cron schedule without guessing which field is which, and read back in plain English what the expression you already have actually does. The five fields — minute, hour, day of month, month, day of week — are easy to write and famously easy to get subtly wrong, so every expression here is range-checked and then described in a sentence before you paste it into a crontab.

Schedule

Minute — 0-59

Hour — 0-23

Day of month — 1-31

Month — 1-12

Day of week — 0-6, Sunday is 0

Accepts a list (1,3,5), a range (1-5) or a step (*/2).

Result

0 0 * * *

Runs at 00:00, every day. Cron reads times in the server's time zone, not yours — if the box runs on UTC, so does this schedule.

Nothing is uploaded — this tool runs inside your browser, so your files never leave your device.

Help us improve

Why use this tool

Nine common presets, from every minute to once a year
Or set all five fields yourself, with lists, ranges and steps
Validates every field against its real range and says which one is wrong
Describes the finished expression in plain English

How it works

1Pick a preset, or choose Custom to fill in the five fields.
2Read the description under the result to confirm it does what you meant.
3Copy the expression into your crontab or CI schedule.

Cron Expression Generator — frequently asked questions

In order: minute (0-59), hour (0-23), day of the month (1-31), month (1-12) and day of the week (0-6, where 0 is Sunday). An asterisk means “every”. So `30 2 * * 1` is 02:30 every Monday.

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