Build Cron Expressions Instantly
Set each field — minute, hour, day of month, month, and weekday — and get a ready-to-use crontab line along with a plain-English explanation.
Everything runs directly in your browser — no data is sent anywhere, and no schedules are stored.
What Is a Cron Expression?
A cron expression is a five-field pattern used by Unix-like systems to schedule commands to run automatically at fixed times, dates, or intervals.
Each field controls a different unit of time — minute, hour, day of month, month, and day of week — and together they define exactly when a job should run.
Cron Field Syntax
| Minute | 0–59 |
| Hour | 0–23 |
| Day of month | 1–31 |
| Month | 1–12 |
| Day of week | 0–6 (0 = Sunday) |
Special Characters
| * | Any value — matches every possible value for that field |
| , | Value list separator — e.g. 1,15 means the 1st and 15th |
| - | Range of values — e.g. 1-5 means Monday through Friday |
| / | Step values — e.g. */15 means every 15 units |
Why Use a Cron Generator?
- Avoid syntax mistakes that silently break scheduled jobs
- See a plain-English explanation before deploying a schedule
- Start from a common example instead of writing from scratch
- Get a ready-to-paste crontab line, with an optional command
- No installation or account required
How to Build a Cron Expression
- Set the minute, hour, day, month, and weekday fields — or pick a common example
- Optionally add the command you want to run
- Check the plain-English explanation to confirm the schedule is correct
- Copy the crontab line and paste it into your crontab file
Cron Best Practices
Prefer specific times over very frequent schedules — running a job every minute when every 5 or 15 minutes would do wastes resources.
When a job depends on both a day of month and a day of week, remember most cron implementations treat the two fields as OR, not AND.
Always log the output of scheduled jobs (e.g. redirect to a file) so failures don't go unnoticed.
Common Use Cases
- Automated database backups
- Log rotation and cleanup jobs
- Scheduled report generation
- Cache warming or invalidation
- Sending periodic email digests
- Syncing data between systems
- Health checks and monitoring pings
- Renewing certificates or tokens
Frequently Asked Questions
What timezone does a cron job run in?
By default, cron uses the system's local timezone. Some platforms let you set a specific timezone per job or per crontab — check your system's documentation.
Can cron expressions include seconds?
Standard Unix cron only supports five fields (minute and above), with no seconds field. Some schedulers, like Quartz, support an optional seconds field, but that's a different format.
What happens if I set both day of month and day of week?
Most cron implementations run the job if either condition matches (an OR, not an AND). To run only on a specific date that also falls on a specific weekday, you generally need extra logic in the script itself.
How can I test a cron expression before using it?
Check the plain-English explanation shown here to confirm it matches your intent, then verify on your actual system with a short-lived test schedule before relying on it in production.
Should I use cron or systemd timers?
Cron is simple and works everywhere, making it ideal for straightforward recurring tasks. systemd timers offer more control (dependencies, logging, missed-run handling) and are a good choice on systems that already use systemd.