Cron Expression Explainer
Paste a cron expression and read what it actually does.
Runs entirely in your browser — nothing you paste is sent to our servers.
Day of month and day of week combine with OR, not AND. A schedule of 0 0 1 * 1 runs on the 1st of the month and every Monday — not only when the 1st happens to be a Monday. And most platforms run cron in UTC, not your local timezone.
What this tool does
Plain-English schedule
Reads the whole expression as a sentence, handling exact times, steps, ranges and lists.
Field by field
Each of the five fields shown separately with its valid range, so you can see which one is wrong.
Honest about scope
Covers the standard 5-field POSIX form. Tells you when an expression is Quartz rather than guessing at it.
Local only
Parsed in your browser — no request, nothing logged.
Frequently asked questions
What are the five fields?
In order: minute (0-59), hour (0-23), day of month (1-31), month (1-12) and day of week (0-6, where 0 is Sunday). An asterisk means every value for that field.
Does this support Quartz expressions?
No, and it tells you rather than guessing. Quartz adds a seconds field and the L, W and hash characters. This tool covers the standard 5-field POSIX form used by crontab, Vercel Cron and Kubernetes CronJobs.
How do step values work?
A step of 15 in the minute field means every 15 minutes. A range can be combined with a step, so 0-30 with a step of 10 means minutes 0, 10, 20 and 30.
What happens if I set both day of month and day of week?
They combine with OR, not AND - the job runs on either. This surprises people: a schedule of "0 0 1 * 1" runs on the 1st of the month AND every Monday, not only when the 1st is a Monday.
Which timezone does a cron run in?
Whatever the machine or platform uses, which is very often UTC rather than your local time. Vercel Cron is UTC. Always check, because a schedule that looks like overnight locally may run mid-afternoon.
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