# Cron expression explainer: run it free, or from your agent

Explains a five-field cron expression in plain English and lists the next five run times in UTC or local time.

## Prompt

Use looot to plan a recurring data job: [what to pull] on this schedule: [cron expression]. 1. Set up https://looot.ai/skill.md. 2. Search the catalog for the endpoint and check its price per call. 3. Explain the cron expression in plain English and list the next five runs in UTC. 4. Work out how many runs a month that is and the monthly cost at that price.

## What it needs

A five-field cron expression or an @ shortcut

## What comes back

- plain English description
- values of each field
- next five run times
- errors that name the field

## Endpoints and providers

None. The tool on the web page runs in the browser and calls no endpoint.

## What it costs

Nothing. The tool on the web page runs in the visitor's browser: no account, no API call and no limit per hour. The prompt above runs the same job from your own looot account with current data, billed per call.

## Read a crontab

Understand an inherited schedule before you change it.

## Catch mistakes

See that 0 0 30 2 * never runs before it reaches production.

## CI schedules

Check a GitHub Actions or Kubernetes CronJob schedule in UTC.

## Count the runs

See how often a job fires so you can size its cost.

## What do the five fields of a cron expression mean?

In order: minute (0 to 59), hour (0 to 23), day of month (1 to 31), month (1 to 12 or JAN to DEC) and day of week (0 to 7 or SUN to SAT, where 0 and 7 are Sunday).

## What does */15 mean in cron?

Every 15th value of that field, starting from the lowest. In the minute field, */15 runs at minutes 0, 15, 30 and 45.

## How do I run a cron job every weekday at 9am?

Use 0 9 * * 1-5. That is minute 0, hour 9, any day of month, any month, Monday through Friday.

## What time zone does cron use?

The server's time zone for classic crontab. GitHub Actions schedules run in UTC, and Kubernetes CronJobs use the controller's zone unless the spec sets timeZone. Switch the run list between UTC and your zone to compare.

## What happens when both day of month and day of week are set?

Standard cron runs the job when either one matches. 0 12 1 * MON runs on the first of the month and on every Monday. The page points this out when it applies.

## Does it support @daily and the other shortcuts?

Yes: @yearly, @annually, @monthly, @weekly, @daily, @midnight and @hourly. @reboot has no schedule, so the page says that instead of guessing.

## Does it support Quartz or seconds fields?

No. A six-field expression, L, W and # are Quartz or Spring extensions. The page flags them rather than explaining them wrongly.

## Related tools

- /free-tools/unix-timestamp-converter
- /free-tools/regex-tester
- /free-tools/curl-to-fetch-converter

## Last reviewed

2026-10-14.