Cron Expression Builder
A crontab generator and explainer in one place. Set the fields to produce a schedule, or paste a cron string to see what it runs and when it fires next.
This cron expression builder works two ways: assemble a crontab line from plain controls, or paste one you already have and read back what it means. For each of the five fields — minute, hour, day of month, month, day of week — you pick every, a specific list, a range, or a step such as every 15 minutes, and the cron string updates as you change them. Drop in an existing schedule and you get a plain-English summary plus the next five run times, so you can confirm that 0 9 * * 1 really does fire at 09:00 every Monday. Nicknames like @daily and @hourly are expanded for you as well.
Five fields: minute, hour, day-of-month, month, day-of-week. Nicknames like @daily expand to 0 0 * * *.
*/15 * * * *Every 15 minutes, every day
- Fri, Jul 31, 2026, 12:45 PM
- Fri, Jul 31, 2026, 01:00 PM
- Fri, Jul 31, 2026, 01:15 PM
- Fri, Jul 31, 2026, 01:30 PM
- Fri, Jul 31, 2026, 01:45 PM
How it works
- 1
Pick build or explain
Use the toolbar toggle to switch between assembling a cron from field controls and pasting an existing expression to decode.
- 2
Set the fields or type the line
In build mode choose every, specific, range or step for the minute, hour, day, month and weekday. In explain mode type the five fields, or click a nickname like @weekly.
- 3
Read the summary and next runs
The result pane shows the live cron string, one sentence describing it, and the next five fire times in UTC or your local zone. Copy the expression once it looks right.
Instant & 100% private — nothing is uploaded
Everything runs locally in your browser. Your code, text and files are processed on your own device and are never sent to a server — so there are no upload waits, no size limits from us, and nothing is ever stored or logged.
Frequently asked questions
- What does the cron expression */15 * * * * mean?
- It runs every 15 minutes. The */15 in the minute field matches minutes 0, 15, 30 and 45; the four remaining asterisks (hour, day of month, month, day of week) mean any, so the job fires four times an hour, all day, every day. Paste it in explain mode and the next-runs list confirms the quarter-hour times.
- How do I write a cron for 9am every weekday?
- Use 0 9 * * 1-5: minute 0, hour 9, any day of the month, any month, and 1-5 for Monday through Friday. The summary reads 'At 09:00, on Monday, Tuesday, Wednesday, Thursday and Friday', which you can copy straight into your crontab.
- What do the five fields in a crontab line stand for?
- 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 or SUN-SAT, where 0 and 7 both mean Sunday). Each field takes a single number, a list like 1,15,30, a range like 1-5, or a step like */10.
- Why do the day-of-month and day-of-week fields both fire?
- When you restrict both, cron treats them as OR rather than AND. So 0 0 1 * 1 runs at midnight on the 1st of the month or on any Monday, whichever comes first. This builder follows that classic rule, which is why the next-runs preview can list more dates than you might expect.
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