Cron expressions: the 5 fields

A cron expression is five fields, always in the same order: minute · hour · day-of-month · month · day-of-week. Each field is either a number, a * (any value), a step like */5 (every 5 units), or a range like 1-5. This is the crontab(5) convention — not a formal IETF or ISO standard, just the near-universal syntax every major cron implementation follows.

A few you’ll see constantly:

• */5 * * * * — every 5 minutes
• 0 2 * * * — 2:00 AM daily
• 0 9 * * 1-5 — 9:00 AM, weekdays only
• 0 9 * * 1 — 9:00 AM, Mondays only

Reading someone else’s cron line is one problem; getting your own right before you paste it into a scheduler is another. TryDevSnip’s cron helper explains an expression in plain English, or builds one for you from a plain-English picker (“every 15 minutes”, “weekdays at 9”, “monthly on the 1st”) — plus a preview of the next few actual run times, so you can catch an off-by-one field before it fires in production. Nothing you paste leaves your browser.