What does */15 9-17 * * 1-5 actually mean?
Every 15 minutes, 9 AM to 5 PM, Monday through Friday. But you had to think about that for a second, right? Cron syntax is compact and powerful, but reading it fluently takes practice most of us never bother with. You write a cron expression, deploy it, and then spend the next hour wondering if your backup script will fire at 4:30 AM or 4:30 PM.
Paste the expression here. You get a plain-English description and the next 5 execution times based on your local clock. If those times look wrong, tweak the expression and check again. Way less stressful than waiting until 4 AM to see if it works.
There’s also a visual cron builder with dropdowns, handy if you don’t want to memorize the field order every single time.
The five fields
┌──── minute (0-59)
│ ┌──── hour (0-23)
│ │ ┌──── day of month (1-31)
│ │ │ ┌──── month (1-12)
│ │ │ │ ┌──── day of week (0-6, Sunday=0)
│ │ │ │ │
* * * * ** means “every.” , separates a list (1,3,5). - makes a range (9-17). / sets an interval (*/15 = every 15).
Expressions you’ll keep coming back for
* * * * *, every minute. Useful for testing, terrifying in production.
0 * * * *, top of every hour.
0 0 * * *, midnight daily. The classic backup schedule.
0 9 * * 1-5, weekdays at 9 AM. Your daily report job.
30 4 * * *, 4:30 AM daily. Low-traffic window maintenance.
0 0 1 * *, midnight on the 1st of each month.
0 */6 * * *, every 6 hours. Common for cache refreshes.
The visual builder
Don’t feel like counting fields? Use the Cron Builder section, dropdowns for minute, hour, day of month, month, and day of week. Pick your values, click “Use This,” and the expression appears in the parser. Beats guessing.
For timestamp-related work, the Unix Timestamp Converter is also on Toolsvu.
FAQ
What format does it support?
Standard 5-field cron, the kind used by crontab, systemd timers, GitHub Actions schedule, and most task schedulers. Six-field and seven-field variants (with seconds or years) aren’t supported.
Does it show when the job will run next?
Yes, 5 upcoming execution times calculated from your current local time.
Can I build expressions without knowing the syntax?
That’s what the Cron Builder is for. Dropdowns for each field, no memorization needed.
Everything’s in my browser?
Client-side JavaScript, no server calls. Your cron expressions stay private.