Crontab generator
Build a five-field cron expression and see a plain-language description, the parsed field values and the next 5 run times, with presets and validation errors.
Runs in your browserEvery computation happens in your browser — your data never leaves this device.
Cron expression
Result
Calculating the next run times…
03* (31)* (12)* (7)What this tool does
- Double-check a crontab before shipping: edit the five fields (minute, hour, day, month, weekday) and watch the plain-language description and next five run times update live.
- Decipher a script somebody else left behind — paste 0 9 * * 1-5 and immediately see it means weekdays at 9.
- Verify "when does it next run": the description is a hint, but the real check is the five computed timestamps, calculated in your local timezone.
- Start from a preset — every minute, every 5 minutes, daily at midnight, weekdays at 9, monthly on the 1st — and tweak one field from there.
Example
Input
0 3 * * *
Output
Description "every day — 3:00" (Chinese: 每天 3:00 执行); parsed values: minute 0, hour 3, day 1-31, month 1-12, weekday 0-6; next 5 runs from 2026-01-01 00:00: 2026-01-01 03:00, 01-02 03:00, 01-03 03:00, 01-04 03:00, 01-05 03:00
All five fields are required; four of them reports "got 4". Run times are computed in the browser’s local timezone — no server timezone is involved.
Frequently asked questions
Why does 0 3 * * * describe as "every day — 3:00"?
The day part is assembled from the day, month and weekday fields: with day and weekday wildcards and no month restriction you get "every day", and the time part becomes 3:00 from the minute and hour values. The Chinese page phrases the same thing as 每天 3:00 执行.
Which syntax is supported?
* , single numbers, ranges (a-b), lists (a,b) and steps: star slash n for the whole field, a-b slash n within a range, and a slash n meaning from a to the field maximum in n-sized steps. In the weekday field both 0 and 7 mean Sunday.
What happens when both day-of-month and weekday are restricted?
The standard cron "or" rule applies: a match on either field triggers the job rather than requiring both. This is commonly misread as "and", so 0 0 1 * 1 runs on the 1st of every month and on every Monday.
Why does 0 0 31 2 * report no upcoming runs?
February 31st does not exist, so after searching five years (the limitDays guard) the tool gives up and says no run time matches within five years. That guard prevents an endless loop and is not a syntax error — the expression itself is valid.
Are six-field (with seconds) expressions or @daily aliases supported?
Neither — only the standard five-field form, and macros such as @daily or @reboot are not recognised. A wrong field count reports how many fields were found, so you can tell whether one is missing or extra. Parsing happens entirely locally.
Keywords：croncrontab定时任务cron 表达式计划任务schedulerexpression generator