Cron Expression Builder

Build a cron expression part-by-part, get a plain-English description, and preview the next five scheduled runs in your timezone. Handles ranges, lists, step values, and named days.

DomainProgrammingVersionv1.0.0Added2026-05-17

Build a cron expression field by field and see exactly what it means before it ever hits your crontab or CI pipeline. Set the minute, hour, day-of-month, month and day-of-week, pick your timezone, and the tool returns the assembled expression, a plain-English description, and a preview of the next five times it will actually fire.

Inputs

Minute

When in the hour. * = every minute. 0 = top of the hour. */15 = every 15 minutes. 0,30 = on the hour and half past.

Hour

Which hour(s), 24-hour clock. 9-17 = 9 AM to 5 PM. * = every hour.

Day of Month

1-31. * = every day. 1,15 = first and fifteenth. Combine with Day of Week for finer control.

Month

1-12 or JAN-DEC. * = every month.

Day of Week

0=Sunday, 6=Saturday. 1-5 = Mon–Fri. Names like MON-FRI also work.

Timezone

Cron expressions are timezone-agnostic by themselves — the timezone tells us when to fire in real time. Pick where your servers actually run.

Result

version1.0.0

POST /v1/programming-dev/cron-expression-builderView API docs →

curl -X POST https://toolsamurai.com/api/v1/programming-dev/cron-expression-builder \
  -H "Authorization: Bearer sk_live_•••••••••••••••" \
  -H "Content-Type: application/json" \
  -d '{
     "minute": "0",
     "hour": "9",
     "day_of_month": "*",
     "month": "*",
     "day_of_week": "1-5",
     "timezone": "Asia/Kolkata"
  }'

cronschedulercronjobautomationtimezonedevops

How it works

The method behind the numbers

A standard cron expression has five fields — minute, hour, day-of-month, month, day-of-week — each accepting a single value, a list (1,15), a range (9-17), a step (*/5), or a wildcard (*). The builder validates each field, assembles the expression, and translates it back into a sentence so you can sanity-check intent against syntax.

The next-run preview is timezone-aware, which is where most cron mistakes hide: a schedule that looks right in UTC can fire at the wrong local hour, and the day-of-month / day-of-week fields combine with an OR in standard cron, not an AND. Seeing the next five concrete timestamps in your chosen timezone catches both traps before they cause a 3 a.m. page.

Worked examples

See it in practice

Every weekday at 9:00 AM

A common business-hours job: minute 0, hour 9, Monday–Friday.

minute: 0
hour: 9
day_of_month: *
month: *
day_of_week: 1-5
timezone: Asia/Kolkata

Every 15 minutes

A frequent polling schedule using a step value.

minute: */15
hour: *
day_of_month: *
month: *
day_of_week: *
timezone: UTC

FAQ

Frequently asked questions

How do day-of-month and day-of-week interact?

In standard (Vixie) cron, when both fields are restricted the job runs when EITHER matches — it's an OR, not an AND. So '0 0 13 * 5' runs on the 13th and on every Friday, not only Friday the 13th. The next-run preview makes this explicit.

What does */5 mean?

A step value: 'every 5th'. In the minute field, */5 fires at minutes 0, 5, 10, … 55. You can combine steps with ranges too — 0-30/10 means minutes 0, 10, 20, 30.

Why does timezone matter for cron?

Cron fires in whatever timezone its host uses. A schedule authored mentally in your local time can run hours off on a UTC server, and daylight-saving transitions can skip or double a run. Previewing concrete timestamps in your timezone removes the guesswork.

Is this standard 5-field cron or the 6-field variant?

It builds the classic 5-field crontab expression used by Unix cron, most CI systems, and Kubernetes CronJobs. The 6-field form (with seconds) used by some schedulers like Quartz isn't produced here.

Embedding

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Cron Expression Builder

Cron schedule + plain-English preview

The method behind the numbers

See it in practice

Frequently asked questions

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