Cron Expression Parser

What this tool does

Cron Expression Parser describes cron schedules in plain language, breaks them down field by field and calculates upcoming and previous run times in any time zone. It supports standard 5-field crontab syntax, 6-field expressions with seconds, ranges, steps, lists, month and weekday names and macros such as @daily.

Cron syntax is compact but unforgiving. Five space-separated fields control the minute, hour, day of month, month and day of week, and a single misplaced asterisk can turn a nightly backup into one that runs every minute for an hour. Reading 0 */6 1,15 * * correctly takes practice, and a wrong schedule is often noticed only after a job fails or runs far too often.

This parser checks the expression, translates it into a sentence and lists exactly when it will fire next. Descriptions come from the cronstrue library and run times from cron-parser, which follow Vixie cron rules: when both day of month and day of week are restricted, a job runs when either matches. Times are calculated in the IANA time zone you choose, including daylight-saving transitions, and the libraries are loaded on demand and run locally.

How to use Cron Expression Parser

1. Type or paste your expression into Cron expression, or pick one from Examples.
2. Read the In plain English summary to confirm the schedule matches your intent.
3. Check the Field breakdown table to see how each of the five or six fields is interpreted.
4. Choose the Time zone your server or scheduler uses, since cron runs in the daemon’s local time.
5. Review Next run times and the previous run, and adjust Next runs to show to look further ahead.
6. Download the run list as CSV if you need to share the schedule with your team.

Tips for better results

• Day of week accepts 0 to 7, where both 0 and 7 mean Sunday, as well as names such as MON-FRI.
• Use step values with a range, such as 0-30/10, to run at minutes 0, 10, 20 and 30 only.
• Kubernetes CronJobs and GitHub Actions use 5-field syntax and run in UTC unless a time zone is configured.
• A 6-field expression starts with seconds, as used by Spring, Quartz-style schedulers and node-cron.

Common use cases

• Checking a crontab line before deploying it to a server.
• Reviewing CI schedules in GitHub Actions or GitLab pipelines.
• Explaining an inherited schedule to a colleague during code review.
• Confirming how a job behaves around a daylight-saving change.

Common mistakes to avoid

• Setting both day of month and day of week, for example 0 0 13 * 5, and expecting only Friday the 13th; standard cron runs on every 13th and every Friday.
• Writing * in the minute field for a daily job, such as * 2 * * *, which runs 60 times between 02:00 and 02:59.
• Scheduling jobs between 01:00 and 03:00 local time in zones with daylight saving, where runs can be skipped or repeated.