Related Tools
How to Use
- 1Enter a 5-field cron expression (minute, hour, day, month, weekday).
- 2Read the human-readable description of your schedule.
- 3View the field-by-field breakdown showing what each part means.
- 4Check the next 5 calculated run times in your local timezone.
- 5Use preset buttons for common schedules like hourly, daily, or weekly.
About Cron Expression Parser
The Cron Expression Parser breaks down standard 5-field cron expressions into a clear, human-readable description and calculates the next 5 execution times in your local timezone. It supports all standard cron syntax: wildcards (*), step values (/), ranges (-), and comma-separated lists — covering every scheduling pattern you can express in cron. The tool validates your input in real time, flagging out-of-range values and malformed fields before you deploy a broken schedule.
Cron syntax, originally introduced in Version 7 Unix by Ken Thompson in 1979, is one of the most powerful scheduling notations in computing, but it is notoriously difficult to read at a glance. An expression like '*/15 9-17 * * 1-5' encodes a precise schedule, but it takes mental effort to parse. This tool instantly translates it to 'Every 15 minutes, between 9:00 AM and 5:00 PM, Monday through Friday' — eliminating guesswork and preventing costly scheduling mistakes that might go unnoticed until a job runs at the wrong time in production. The plain-English description removes ambiguity that is common even among experienced engineers.
The five fields in a standard cron expression represent, in order: minute (0-59), hour (0-23), day of month (1-31), month (1-12 or Jan-Dec), and day of week (0-6, where 0 is Sunday, or Sun-Sat). Each field can contain a single value (5), a wildcard (*), a range (1-5), a list (1,3,5), or a step value (*/10). Combining these operators gives you fine-grained control over exactly when a job executes. The format is documented in the crontab(5) man page on Linux systems and is the de facto standard used by virtually every scheduling system in the Unix and cloud ecosystem.
Common cron patterns every developer should know include: '0 * * * *' (every hour on the hour), '0 0 * * *' (midnight every day), '0 9 * * 1-5' (weekdays at 9 AM), '*/5 * * * *' (every 5 minutes), '0 0 1 * *' (first of every month at midnight), and '0 0 * * 0' (every Sunday at midnight). The preset buttons in this tool generate these common patterns with one click, so you do not have to memorize the syntax. You can also use them as starting points, tweaking the generated expression to match your exact requirements.
This tool is built for DevOps engineers configuring scheduled tasks in Linux crontab, Kubernetes CronJobs, AWS EventBridge (formerly CloudWatch Events), GitHub Actions scheduled workflows, GitLab CI/CD pipeline schedules, Azure Functions timer triggers, and cloud-based job schedulers like Cloud Scheduler on Google Cloud. Getting a cron schedule wrong can have real consequences — a backup job running at the wrong hour, a report generating at peak traffic time, a cleanup task firing daily instead of weekly, or a billing job missing its end-of-month window. Always verify your expression before deploying to any environment.
All parsing and time calculation runs entirely in your browser using JavaScript. No data is transmitted to any server, and no cron expressions are logged or stored. The next run times are computed by iterating forward from the current moment in your local timezone, matching the behavior of your system's actual cron daemon. Keep in mind that server-side cron typically runs in UTC, so compare the displayed local times against your server's timezone configuration to avoid off-by-hours scheduling errors.
Frequently Asked Questions
What cron format does this tool support?
Standard 5-field cron format: minute (0-59), hour (0-23), day of month (1-31), month (1-12 or Jan-Dec), and day of week (0-6 where Sunday is 0, or Sun-Sat). This is the format used by Linux crontab, Kubernetes CronJobs, GitHub Actions, and most scheduling systems worldwide.
Does it support seconds or year fields?
No. This parser handles the standard 5-field format used by crontab and most scheduling systems. Extended 6-field formats (with seconds, used by Quartz and Spring) or 7-field formats (with year) are not supported. If you need seconds-level scheduling, most platforms offer alternative syntax or separate configuration for sub-minute intervals.
Are the next run times accurate?
Yes. Run times are calculated by iterating forward from the current moment in your local timezone, matching what your system's cron daemon would schedule. The tool accounts for month lengths, leap years, and day-of-week constraints. Results are displayed in your browser's local timezone.
Can I use this for Kubernetes CronJobs?
Yes. Kubernetes CronJobs use standard 5-field cron syntax, identical to Linux crontab. Paste the schedule field from your CronJob manifest to verify the timing before applying it to your cluster. This is especially important in production environments where a misconfigured schedule can cause resource contention or missed processing windows.
What does */5 mean in a cron expression?
The */ syntax means 'every N units.' In the minute field, */5 means every 5 minutes (0, 5, 10, 15, 20, ..., 55). In the hour field, */5 means every 5 hours (0, 5, 10, 15, 20). You can also use step values with ranges: 1-30/5 in the minute field means every 5 minutes between minute 1 and minute 30.
What is the difference between * and ?
In standard 5-field cron (which this tool supports), only * is used as the wildcard. The ? character is specific to 6/7-field cron implementations like Quartz and Spring, where it means 'no specific value' in the day-of-month or day-of-week field to avoid conflicts. In standard cron, use * for both.
How do I schedule a job to run on the first and fifteenth of each month?
Use a comma-separated list in the day-of-month field: '0 0 1,15 * *' runs at midnight on the 1st and 15th of every month. You can combine this with specific hours: '0 9 1,15 * *' runs at 9 AM on those days.
Can a cron expression schedule a job to run every 45 seconds?
No. Standard cron's smallest unit is one minute. For sub-minute scheduling, you need a different approach: run the job every minute with internal logic to handle the sub-minute interval, use a task queue (like Celery, Bull, or Sidekiq), or use a systemd timer with OnUnitActiveSec for Linux systems.