# Cron Expression Explainer

> Free cron expression explainer. Paste a cron schedule and get a plain-English description plus upcoming run times. All client-side.

Paste a cron expression and get a plain-English description of when it runs, plus the next few scheduled times. No more guessing what 0 4 * * 1 means.

*Interactive tool: enter your values at https://toollantern.win/cron-expression-explainer/ and results update instantly in your browser.*

## What the tool does

Cron schedules follow the pattern minute hour day-of-month month day-of-week. This tool parses each field and describes it in words, then computes the next few actual run times from your current clock so you can sanity-check the schedule.

## Worked example

*/15 9-17 * * 1-5 means: every 15 minutes, during hours 9 to 17, every day of the month, every month, on weekdays (Monday to Friday). A classic business-hours polling schedule.

## Field reference

Minute 0-59, hour 0-23, day of month 1-31, month 1-12 (or JAN-DEC), day of week 0-7 where both 0 and 7 mean Sunday (or SUN-SAT). * means every, */n every n, a-b a range, a,b a list.

## Frequently asked questions
### What is cron?

The time-based job scheduler on Unix-like systems. You write a five-field expression describing when something should run, and the cron daemon runs it on that schedule.

### Do day-of-month and day-of-week combine with AND or OR?

OR, in classic cron: the job runs when either field matches. So '0 0 1 * 0' runs on the 1st of the month AND every Sunday. This is the most common cron gotcha.

### Why does my cron job not run?

Usual suspects: wrong field order, missing newline at end of crontab, environment differences (cron has a minimal PATH), or the daemon not running. Test the expression here first.

### Is my expression sent to a server?

No. Parsing and next-run computation happen locally in your browser.

---
Interactive version: https://toollantern.win/cron-expression-explainer/