Setting up a new crontab entry, Kubernetes CronJob , GitHub Actions schedule, or AWS EventBridge rule. Translating a "run every weekday morning" requirement into a syntactically correct cron line. Sanity-checking that an expression you've drafted will actually run when you think it will, before deploying. Onboarding someone new to cron — let the dropdowns and the preview teach the syntax.

Day-of-month + day-of-week interact. Most cron implementations OR them when both are restricted: * * 15 * 1 fires on the 15th OR a Monday, not "the 15th if it's a Monday". Timezone is your browser's local zone here. Real cron daemons run in the server's timezone (often UTC). Confirm before pasting into a server. */N isn't quite "every N". */15 in minutes = 0,15,30,45 — not 12,27,42,57. Use a list if you need a specific phase. Step + range combos. 0-30/5 covers 0,5,10,15,20,25,30 only. Some cron flavours add fields. Quartz cron has 6 or 7 fields (with seconds and year). systemd timers use a totally different format. This builder targets the standard 5-field crontab. Friday-the-13th is hard to express in cron. Cron's day-of-month and day-of-week interact via OR, so combining them strictly requires a wrapper script.

Cron Expression Builder

Visually build a cron expression — minute, hour, day, month, weekday — and preview the next 5 fire times.

Preset

Minute (0–59)

Hour (0–23)

Day of month (1–31)

Month (1–12)

Day of week (0=Sun – 6=Sat)

Cron expression

0 9 * * 1-5

Next 5 fire times (local timezone)

Enter input above to see the result.

What is this for?

Cron syntax is famously dense — five fields, each accepting wildcards, ranges, lists, and steps. Writing one from scratch every time invites typos. This builder lets you start from a preset (every-5-minutes, weekdays-at-09:00, etc.) or type into individual fields, see the resulting cron string, get a plain-English summary, and confirm against the next five real fire times in your local timezone. The complement to this is the Cron Expression Parser, which decodes an existing expression into the same preview.

When to use it

Setting up a new crontab entry, Kubernetes CronJob, GitHub Actions schedule, or AWS EventBridge rule.
Translating a "run every weekday morning" requirement into a syntactically correct cron line.
Sanity-checking that an expression you've drafted will actually run when you think it will, before deploying.
Onboarding someone new to cron — let the dropdowns and the preview teach the syntax.

Field syntax cheat sheet

* — every value in the field's range.
*/N — every Nth (starting at the lower bound).
A-B — range, inclusive.
A,B,C — list of specific values.
A-B/N — every Nth within range A–B.

Common gotchas

Day-of-month + day-of-week interact. Most cron implementations OR them when both are restricted: * * 15 * 1 fires on the 15th OR a Monday, not "the 15th if it's a Monday".
Timezone is your browser's local zone here. Real cron daemons run in the server's timezone (often UTC). Confirm before pasting into a server.
*/N isn't quite "every N". */15 in minutes = 0,15,30,45 — not 12,27,42,57. Use a list if you need a specific phase.
Step + range combos. 0-30/5 covers 0,5,10,15,20,25,30 only.
Some cron flavours add fields. Quartz cron has 6 or 7 fields (with seconds and year). systemd timers use a totally different format. This builder targets the standard 5-field crontab.
Friday-the-13th is hard to express in cron. Cron's day-of-month and day-of-week interact via OR, so combining them strictly requires a wrapper script.