Cron Expression Generator
Build and explain cron expressions in plain English. Use presets or per-field inputs, then copy a verified schedule — all processed privately in your browser.
Build by field
0-59
0-23
1-31
1-12
0-6 (Sun=0)
This schedule runs
At 09:00 AM
Everything is generated and parsed in your browser — nothing is ever uploaded or stored.
Cron Expression Generator and Explainer
Cron expressions are the standard way to schedule recurring tasks on Unix-like systems, in CI pipelines, and in cloud schedulers — but their terse five-field syntax is easy to get wrong. A single misplaced asterisk can turn "every day at midnight" into "every minute," and the only feedback you usually get is a job that fires at the wrong time. This tool removes the guesswork: build a schedule from labelled fields or a preset, and read back exactly what it means in plain English before you commit it anywhere.
How to Build a Schedule
- Start from a preset such as "Weekdays at 9am" or "Every 15 minutes" to get a valid expression instantly.
- Edit individual fields — minute, hour, day of month, month, and day of week — and the expression rebuilds live.
- Type a raw expression directly if you already have one; the fields and description stay in sync.
- Read the description in the highlighted box to confirm the schedule, then copy it with one click.
Common Patterns and Tips
Use * for "every," a */n step for intervals (*/10 = every ten),
ranges like 1-5 for Monday–Friday, and comma lists like 0,30 for multiple
fixed values. Remember that day-of-month and day-of-week are both present, so 0 0 1 * 1
can behave differently than you expect depending on the scheduler. When the expression is invalid the
description box turns red immediately, so you catch mistakes long before a job misfires in production.
Privacy
All parsing and description happens in your browser using client-side JavaScript. Your schedules are never uploaded, transmitted, or stored on any server, making this safe for drafting cron jobs for private infrastructure, internal tooling, or confidential projects.
Frequently Asked Questions
What do the five cron fields mean?↓
A standard cron expression has five space-separated 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. For example, 0 9 * * 1-5 means "at 9:00 AM, Monday through Friday." This tool labels each field for you so you never have to remember the order.
How do I run a job every few minutes or hours?↓
Use step values with a slash. */5 * * * * runs every 5 minutes, and 0 */2 * * * runs every 2 hours on the hour. You can also use ranges (1-5), lists (1,15,30), or combine them (0,30 9-17 * * *) for "on the hour and half-hour between 9 AM and 5 PM." Pick a preset to see a working example, then tweak the individual fields and watch the plain-English description update instantly.
Why does my cron expression say it is invalid?↓
The most common causes are using more or fewer than five fields, putting a value outside the allowed range (such as hour 24 or month 13), or mixing up the day-of-month and day-of-week positions. Reversed ranges like 5-1 and stray characters also fail. The live description box turns red and tells you the moment an expression cannot be parsed, so you can fix it before deploying it to crontab, GitHub Actions, or a scheduler.
Is my cron expression sent to a server?↓
No. Both the generator and the human-readable explainer run entirely as JavaScript inside your browser tab. Nothing you type — fields, raw expressions, or schedules — is ever uploaded, logged, or stored. That makes it safe to draft schedules for internal infrastructure or private projects without anything leaving your device.