Which cron syntax is this?

Standard 5-field POSIX cron — minute, hour, day-of-month, month, day-of-week. The same format used by crontab and most modern serverless schedulers.

Can I express 'every Monday and Wednesday at 9am'?

Yes — switch to Custom and set day-of-week to '1,3'. The Cron Explainer tool will translate it back into 'At 09:00 on Monday and Wednesday' so you can sanity-check.

Why is day-of-month / day-of-week confusing together?

In standard cron these are OR'd: '0 9 1 * 1' means 1st of the month OR every Monday at 9. Most schedulers honor this rule; a few quirky ones don't. Test in your target system.

Standard cron doesn't have a seconds field — its smallest grain is one minute. For second-level granularity you'd use Quartz cron (6/7 fields), which this tool doesn't generate.

Cron Expression Builder

Pick a frequency (every minute / hour / day / week / month / custom) and the tool generates the 5-field cron expression for you, with a plain-language description that always matches. Custom mode exposes all five fields if you need fine-grained control. The output is standard POSIX cron — works with crontab, GitHub Actions, Vercel Cron, Cloudflare Cron Triggers, and most schedulers.

—

Frequency

HourMinute

Cron expression

0 9 * * *

Plain language: Every day at 09:00

How to use

Pick a frequency.
For 'every day' / 'every week' / 'every month', set the hour, minute, weekday, or day-of-month.
For totally custom schedules, switch to Custom and edit each field directly.
Copy the cron expression.

Frequently asked questions

Which cron syntax is this?: Standard 5-field POSIX cron — minute, hour, day-of-month, month, day-of-week. The same format used by crontab and most modern serverless schedulers.
Can I express 'every Monday and Wednesday at 9am'?: Yes — switch to Custom and set day-of-week to '1,3'. The Cron Explainer tool will translate it back into 'At 09:00 on Monday and Wednesday' so you can sanity-check.
Why is day-of-month / day-of-week confusing together?: In standard cron these are OR'd: '0 9 1 * 1' means 1st of the month OR every Monday at 9. Most schedulers honor this rule; a few quirky ones don't. Test in your target system.
What about seconds?: Standard cron doesn't have a seconds field — its smallest grain is one minute. For second-level granularity you'd use Quartz cron (6/7 fields), which this tool doesn't generate.

Guides on this topic

How Cron Schedules Actually Work The five cron fields and their syntax, the day-of-month/day-of-week rule almost everyone gets wrong, what daylight saving does to a nightly job, and how to design schedules that survive restarts.

Related tools

Cron Expression Explainer

Translate a cron expression into plain English (or your language) and break down each field.

Developer 0 0

Cron Next Runs

Type a 5-field cron expression and see the next N times it will fire — local time, including weekday + day-of-month dual semantics.

Time 0 0

CSS Flexbox Playground

Visually pick flex-direction, justify-content, align-items, and gap — copy the resulting CSS or Tailwind class.

Developer 0 0

CSS Grid Playground

Visually pick grid-template-columns / rows, gap, and item alignment — copy the CSS straight into your project.

Developer 0 0

Regex Tester

Test JavaScript regular expressions live with highlighted matches and replace preview.

Developer 0 0

Conventional Commit Message Builder

Build a Conventional Commits message with type, scope, breaking change, and footers, in your browser.

Developer 0 0