Crontab Expression Explainer
Last updated:
Paste a cron expression — get a plain-English description and the next 5 actual run times, in your browser's local time zone. Correctly handles cron's day-of-month/day-of-week OR rule. All in your browser, nothing uploaded.
How it works
- Another interactive explainer, not a Format/Minify/To-JSON triad — one expression in, a plain-English description and the next 5 actual run times out.
- Covers the standard 5-field cron format (minute hour day-of-month month day-of-week) used by crontab, GitHub Actions’
schedule: cron:, and Kubernetes CronJob — lists, ranges, steps, and the@yearly/@monthly/@weekly/@daily/@hourly/@rebootmacros. Month and day-of-week accept both numbers and three-letter names. - Gets cron’s single most commonly misread rule right: when BOTH day-of-month and day-of-week are restricted (neither is a bare
*), a date matches if EITHER one matches — it’s OR, not AND.0 0 1,15 * MONmeans midnight on the 1st, the 15th, or any Monday, not “the 1st/15th and also a Monday.” This tool computes the next run times using that real rule and calls it out explicitly in the description whenever it applies. - Next-run times are computed by walking forward from right now and shown in your browser’s local time zone — matching how a real crontab, which runs in the system’s local time by default, would actually fire. An expression that can structurally never occur (like day 31 in a month that never has one) is reported as such.
Runs entirely in your browser — nothing you type here is uploaded, logged, or stored.