Cron expression guide

A cron expression is five fields that say when a scheduled job should run. Here is how to read and write them.

The five fields

┌─────────── minute (0-59)
│ ┌───────── hour (0-23)
│ │ ┌─────── day of month (1-31)
│ │ │ ┌───── month (1-12)
│ │ │ │ ┌─── day of week (0-6, Sun=0)
│ │ │ │ │
* * * * *

Some schedulers add a leading seconds field, making a 6-field expression. CronKit understands both.

Special characters

Character	Meaning	Example
`*`	every value	`* * * * *` — every minute
`*/n`	every n steps	`/15 * * *` — every 15 minutes
`a-b`	a range	`0 9 * * 1-5` — weekdays at 9 AM
`a,b`	a list of values	`0 0 * * 6,0` — Saturday and Sunday
`L`	last day of month	`0 0 L * *` — last day at midnight

Compute next runs in code

curl

curl "https://cron.wrapper-agency.com/api/v1/cron?expr=0 9 * * 1-5&tz=UTC"

JavaScript (fetch)

const res = await fetch(
  "https://cron.wrapper-agency.com/api/v1/cron?expr=" + encodeURIComponent("0 9 * * 1-5")
);
const { human, nextRuns } = await res.json();
console.log(human);            // "At 09:00 AM, Monday through Friday"
console.log(nextRuns[0].iso);  // next run as ISO timestamp

Python (requests)

import requests
r = requests.get(
    "https://cron.wrapper-agency.com/api/v1/cron",
    params={"expr": "0 9 * * 1-5", "tz": "Europe/Paris"},
)
print(r.json()["human"])

Common expressions

Run every minute — * * * * *
Run every 5 minutes — */5 * * * *
Run every 10 minutes — */10 * * * *
Run every 15 minutes — */15 * * * *
Run every 30 minutes — */30 * * * *
Run every hour — 0 * * * *
Run every 2 hours — 0 */2 * * *
Run every 6 hours — 0 */6 * * *
Run every 12 hours — 0 */12 * * *
Run every day (at midnight) — 0 0 * * *
Run every weekday — 0 0 * * 1-5
Run every weekend — 0 0 * * 6,0
Run every week (Sunday) — 0 0 * * 0
Run every month (1st) — 0 0 1 * *
Run every year — 0 0 1 1 *

See the full cron API reference, or start from the explainer & builder.