Cron Expression Builder

How to use

1. Pick how often the job should run.
2. Fill in the time, days or date the frequency asks for.
3. Check the next run times underneath — they are produced by parsing the expression, not by the builder.
4. Copy the expression into your crontab, CI schedule or scheduler config.

Features

• Every frequency from every-minute to once a year.
• Previews the next five runs by parsing what it just built.
• Refuses dates that never happen, such as 30 February, instead of emitting a job that silently never runs.
• Common expressions listed for copying, with the check that each one parses.

Frequently asked questions

Which time zone does a cron expression use?

The one the machine or scheduler is set to, which is frequently UTC on servers and local time on a laptop. Cron has no field for a zone, so the same expression fires at different moments in different places. The preview here is UTC so you have a fixed reference; confirm your scheduler’s zone before relying on an exact hour.

Why can I not set both a day of the month and a weekday?

Because cron treats those two fields as OR, not AND: with both restricted, the job runs on days matching either one. That surprises almost everyone, so this builder only lets you set one at a time. If you genuinely want that behaviour, write it by hand and check it in the cron parser.

Does */5 mean every five minutes exactly?

It means every minute whose number divides by five — 0, 5, 10 and so on — so it restarts at the top of each hour rather than counting five minutes from the last run. For most intervals that is the same thing. For intervals that do not divide 60, such as */7, it is not: the gap across the hour boundary is shorter.

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