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How to Use Cron Expression Parser — Complete Guide

Learn how to read, write, and validate cron expressions using Tools.Town's free Cron Expression Parser — see the next run times in plain English.

8 May 2026 4 min read By Tools.Town Team Fact Checked

Key Takeaways

  • A cron expression is a string of 5 (or 6) space-separated fields that define a repeating schedule: minute, hour, day-of-month, month, day-of-week
  • '*/5' means 'every 5 units'
  • Standard Unix cron has 5 fields (minute to day-of-week)
  • Most commonly a timezone mismatch — the server runs in UTC but you wrote the schedule in local time

What is Cron Expression Parser?

Cron Expression Parser takes any cron expression, validates it, translates it into plain English, and shows the next 10 scheduled run times. Stop mentally parsing 0 9 * * 1-5 — paste it in and instantly see “Every weekday at 9:00 AM.”

Cron is the universal scheduling language — it runs behind GitHub Actions, AWS Lambda EventBridge, Kubernetes CronJobs, and almost every Linux task scheduler. Understanding it unlocks automation everywhere.


The Five (or Six) Cron Fields

Minute (0–59)

When in the hour the job runs. '0' = on the hour, '30' = half past, '*/15' = every 15 minutes.

Hour (0–23)

24-hour clock. '9' = 9 AM, '17' = 5 PM, '*/2' = every 2 hours.

Day of Month (1–31)

Which day of the month. '1' = 1st, '15' = 15th, '*' = every day.

Month (1–12)

Which month. '1' = January, '12' = December, '*/3' = quarterly.

Day of Week (0–6)

0 = Sunday, 1 = Monday … 6 = Saturday. '1-5' = weekdays, '6,0' = weekends.


How to Use Cron Expression Parser

Enter the expression

Paste or type your cron expression in the input field (e.g. '0 9 * * 1-5').

See validation

The parser instantly flags invalid fields and shows the specific error.

Read the plain English

The human-readable description appears below the input (e.g. 'Every weekday at 9:00 AM').

Check next run times

Scroll down to see the next 10 timestamps when the job will fire.


Common Cron Expressions

ExpressionMeaning
* * * * *Every minute
0 * * * *Every hour, on the hour
0 9 * * 1-59 AM every weekday
0 0 * * *Daily at midnight
0 0 1 * *1st of every month at midnight
*/15 * * * *Every 15 minutes
0 9,17 * * 1-59 AM and 5 PM on weekdays
0 0 * * 0Every Sunday at midnight

Tips & Common Mistakes

Always paste into the parser before deploying. It takes 5 seconds and saves you from a midnight “why did this run 60 times?” incident.

Day-of-month and day-of-week interact oddly. When both fields are set (not *), most cron implementations fire if EITHER condition matches — not both. Use * in one field to avoid surprises.

Timezones bite everyone. Cron servers almost always run in UTC. Write your expressions in UTC and convert to your local time only for documentation.


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Frequently Asked Questions

What is a cron expression?
A cron expression is a string of 5 (or 6) space-separated fields that define a repeating schedule: minute, hour, day-of-month, month, day-of-week. Used by Unix cron, GitHub Actions, AWS EventBridge, and most schedulers.
What does '*/5' mean in cron?
'*/5' means 'every 5 units'. In the minute field, '*/5' means every 5 minutes. In the hour field, '*/2' means every 2 hours.
What is the difference between 5-field and 6-field cron?
Standard Unix cron has 5 fields (minute to day-of-week). Many modern schedulers add a 6th field for seconds at the start. The parser handles both.
Why does my cron expression run at unexpected times?
Most commonly a timezone mismatch — the server runs in UTC but you wrote the schedule in local time. Always confirm which timezone your scheduler uses.

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