What is a cron expression?

A cron expression is a string of five space-separated fields that represent a schedule. The fields are: minute (0-59), hour (0-23), day of month (1-31), month (1-12), and day of week (0-6). For example, '0 9 * * 1-5' means 9:00 AM every weekday.

How do I validate a cron expression?

Enter your cron expression in the input field on crontab.space. The validator instantly checks the syntax and shows any errors. Valid expressions display a human-readable description and the next 5 scheduled execution times.

What does the asterisk (*) mean in cron?

The asterisk (*) in a cron expression means 'every' or 'any value'. For example, * in the minute field means every minute, and * in the day field means every day of the month.

How do I schedule a cron job to run every 5 minutes?

To run a cron job every 5 minutes, use the expression '*/5 * * * *'. The */5 in the minute field means every 5th minute, and the asterisks in other fields mean any hour, day, month, and weekday.

Can I generate a cron expression using natural language?

Yes. crontab.space features an AI-powered generator. Type your schedule in plain English like 'every Monday at 9am' or 'twice daily' and the AI generates the correct cron expression for you.

How do I run a cron job every weekday?

Use '0 9 * * 1-5' to run at 9:00 AM Monday through Friday. The 1-5 in the day-of-week field is a range covering Monday (1) to Friday (5). Change the first two fields to set a different time.

What does */15 * * * * mean?

'*/15 * * * *' runs a job every 15 minutes, all day, every day. The */15 is a step value in the minute field (minutes 0, 15, 30, 45). The remaining asterisks mean any hour, day of month, month, and day of week.

Why isn't my cron expression working?

The most common causes are: the schedule uses the server time zone (often UTC, not local time); day-of-month and day-of-week are combined with OR, not AND; standard Unix cron has no seconds field (six-field syntax is Quartz/Spring); and Sunday can be both 0 and 7. Validate the expression here to see exactly when it will run next.

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At 0 minutes past the hour, every 12 hours, every day

0 */12 * * *

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What does `0 /12 * *` mean?

The cron expression 0 */12 * * * runs at 0 minutes past the hour, every 12 hours, every day. Cron expressions have five fields — minute, hour, day of month, month, and day of week. Enter this schedule in your crontab to run a command on exactly this cadence.

Next 5 runs (UTC)

Sat, May 16, 2026, 12:00 AM

Sat, May 16, 2026, 12:00 PM

Sun, May 17, 2026, 12:00 AM

Sun, May 17, 2026, 12:00 PM

Mon, May 18, 2026, 12:00 AM

Related cron expressions

Every minute Every 5 minutes Every 15 minutes Every hour, on the hour Every 6 hours Every day at midnight Every day at 9:00 AM 9:00 AM, Monday through Friday Midnight every Sunday Midnight on the 1st of every month Every 15 min, 9 AM-5 PM, weekdays 2:30 AM every Saturday

At 0 minutes past the hour, every 12 hours, every day

What does 0 */12 * * * mean?

Next 5 runs (UTC)

Related cron expressions

What does `0 /12 * *` mean?