Which cron dialect does this build?

Expressions follow common five-field Unix cron (minute hour day-of-month month day-of-week) unless the UI labels a sixth field explicitly.

How do day-of-month and day-of-week interact?

Many engines treat OR logic when both are set — read your scheduler docs (cron, Kubernetes, AWS EventBridge) to avoid surprises.

Are next run times in local time or UTC?

Confirm the timezone badge in the tool; production schedulers often store UTC while you design in local time.

Can I model @reboot or @yearly shortcuts?

Use the explainer or paste vendor-specific macros separately — not every platform implements named schedules.

Why five preview fires?

Seeing a short horizon catches off-by-one day mistakes before you deploy to prod crontab.

Does this validate leap years?

Good libraries honour calendar rules — still smoke-test February and 31-day boundaries for financial jobs.

Can I share the expression?

Copy the built string into runbooks, Terraform comments, or GitHub Actions cron YAML.

Is anything uploaded?

Scheduling math runs locally in your browser session.

Cron Expression Builder

Dev Live

Build and explain cron expressions visually.

About this tool

Cron Expression Builder — Build and explain cron expressions visually. Free, fast and private. Runs entirely in your browser at Quick Calci Tools.

Examples

Common scenarios for the Cron Expression Builder.

Every weekday at 9 AM

0 9 * * 1-5 — At 09:00 AM, Monday through Friday.

First of every month

0 0 1 * * — At 00:00 on the 1st day of every month.

Who uses the Cron Expression Builder?

Common scenarios and audiences for this tool.

DevOps engineers

Draft backup and vacuum windows before editing server crontabs.

Data engineers

Align Airflow external triggers with legacy cron neighbours.

SREs

Document on-call rotation reminders with human-readable explanations.

Indie hackers

Schedule Stripe reconciliation scripts on VPS hosts.

Students

Learn field order without memorising man-page tables.

Frequently asked questions

Everything you need to know about the Cron Expression Builder.