Cron Expression Generator

Cron expression generator with human-readable explanation

A cron expression is five fields — minute, hour, day-of-month, month, day-of-week — that tell a scheduler when to run a job. The syntax is famously hostile: 0 0 * * 0 means "every Sunday at midnight" and */15 9-17 * * 1-5 means "every 15 minutes, business hours, weekdays". This tool lets you build expressions visually, see a plain-English description, and preview the next 5 actual run times in your local timezone.

How to read a cron expression

┌──────────── minute (0-59)
│ ┌────────── hour (0-23)
│ │ ┌──────── day of month (1-31)
│ │ │ ┌────── month (1-12)
│ │ │ │ ┌──── day of week (0-6, Sunday=0)
│ │ │ │ │
* * * * *

Each field accepts: a number (5), a range (1-5), a list (1,3,5), a wildcard (*), or a step (*/15, 0-30/5). Steps are the trickiest part: */15 in the minute field means "every 15 minutes starting at 0" — so 0, 15, 30, 45.

Common patterns

• * * * * * — every minute
• */5 * * * * — every 5 minutes
• 0 * * * * — every hour on the hour
• 0 9 * * 1-5 — 9 AM on weekdays
• 0 0 1 * * — midnight on the 1st of every month
• 0 2 * * 0 — 2 AM every Sunday
• 15,45 * * * * — at :15 and :45 of every hour

Pitfalls people hit

• Day-of-month + day-of-week: in standard Unix cron, when both are specified, the job runs when either matches — not both. 0 0 1 * 1 runs on the 1st of every month and every Monday.
• Step starts at 0: */15 in the hour field is 0,15 — but the hour field is 0-23, so this only fires at midnight and quarter-past midnight, not what most people expect.
• Timezone: the cron daemon runs in the server's timezone, not yours. The "next run" preview here uses your browser's local timezone — translate carefully when deploying.
• Jenkins / Quartz are different: Quartz cron has 6 or 7 fields (with seconds and year). Spring's cron has 6. AWS EventBridge uses 6 with year. This tool generates standard 5-field Unix cron.

Where this format applies

Standard 5-field cron is used by Linux crontab, GitHub Actions schedules, GitLab CI scheduled pipelines, Vercel Cron Jobs, Cloudflare Workers cron triggers, Supabase pg_cron (with seconds), Kubernetes CronJob, and most other modern schedulers. If your scheduler uses a different dialect (Quartz, Spring, AWS), validate the generated expression in their docs before deploying.

Testing your expression

Always check the "Next 5 runs" preview before saving. The most common bugs are typos that produce a valid-looking expression that fires at the wrong time — for example 0 0 * * 7 (invalid: day-of-week is 0-6) silently becomes "never" on some implementations.

Related tools

FAQ