WordPress Cron Job Without Plugin

A wordpress cron job no plugin setup is three pieces of code in functions.php: a custom interval (optional), a wp_schedule_event call guarded by wp_next_scheduled, and an add_action for your event hook. WordPress’s WP-Cron API handles the scheduling; you just tell it what to run and when. This guide covers the full pattern, how to clear stale events, and why you’ll probably also want to pair it with a real system cron — covered in the companion guide.

Contents

TL;DR
Step 1 — Custom interval (optional)
Step 2 — Register the recurring event
Step 3 — The callback
Clearing and inspecting
The low-traffic caveat
Frequently asked questions
Related guides
References

Last verified: 2026-04-23 on WordPress 6.5 and PHP 8.3. Originally published 2024-02-23, rewritten and updated 2026-04-23.

TL;DR

// 1. Custom interval (skip if 'hourly'/'daily'/'weekly' fits)
add_filter( 'cron_schedules', function ( $schedules ) {
    $schedules['every_15_min'] = array(
        'interval' => 15 * 60,
        'display'  => __( 'Every 15 Minutes', 'how7o' ),
    );
    return $schedules;
} );

// 2. Register the event (only if not already scheduled)
add_action( 'init', function () {
    if ( ! wp_next_scheduled( 'how7o_cron_event' ) ) {
        wp_schedule_event( time(), 'every_15_min', 'how7o_cron_event' );
    }
} );

// 3. The callback that runs
add_action( 'how7o_cron_event', 'how7o_run_cron_job' );
function how7o_run_cron_job() {
    // Do something here — update prices, send digest, etc.
}

Step 1 — Custom interval (optional)

function how7o_cron_intervals( $schedules ) {
    $schedules['1hr_cron'] = array(
        'interval' => 3600,                  // in seconds
        'display'  => __( '1hr Interval', 'how7o' ),
    );
    return $schedules;
}
add_filter( 'cron_schedules', 'how7o_cron_intervals' );

Skip this if one of WordPress’s built-in intervals fits — hourly, twicedaily, daily, weekly. Define a custom interval only when you need something the built-ins don’t cover. The interval is in seconds; display is what shows up in plugins that list cron events.

Step 2 — Register the recurring event

function how7o_register_cron_event() {
    if ( ! wp_next_scheduled( 'how7o_cron_event' ) ) {
        wp_schedule_event( time(), '1hr_cron', 'how7o_cron_event' );
    }
}
add_action( 'init', 'how7o_register_cron_event' );

Three parts:

wp_next_scheduled('how7o_cron_event') returns the timestamp of the next scheduled run, or false if none. The guard means we only schedule if it’s not already scheduled.
time() is the first run timestamp — “start from now.”
'1hr_cron' (or whichever interval slug) is how often it repeats.
'how7o_cron_event' is the action hook WordPress fires on each run.

wordpress cron job no plugin — cron_schedules filter + wp_schedule_event + action callback

Step 3 — The callback

function how7o_run_cron_job() {
    // Your actual work: update data, call an API, send emails.
    // Keep this fast — long-running cron can time out.
}
add_action( 'how7o_cron_event', 'how7o_run_cron_job' );

The hook name you registered in step 2 (how7o_cron_event) is what WordPress fires on each run — attach your function to that. Keep the callback fast. If the work is heavy (scanning thousands of posts, calling an external API per post), queue an Action Scheduler or batch-mode job from the cron callback rather than doing it all inline.

Clearing and inspecting

// Remove every queued instance of the event
wp_clear_scheduled_hook( 'how7o_cron_event' );

// Inspect everything currently in the cron queue
$cron = get_option( 'cron' );
var_dump( $cron );

Useful during development. Always run wp_clear_scheduled_hook before switching from one interval to another — otherwise both the old and new schedule coexist. On deactivation of a plugin that registered the event, call wp_clear_scheduled_hook in the deactivation hook so the queue doesn’t accumulate orphan events.

The low-traffic caveat

WP-Cron runs on-page-load: every request checks if any cron event is due and fires them in-process. On a high-traffic site this is fine — there’s always a visitor to trigger it. On a low-traffic site, a cron scheduled for 2am may not fire until someone visits at 9am. For time-sensitive work, disable WP-Cron and hit wp-cron.php from a real system cron — walkthrough in How to Set Up a System-Based Cron Job in WordPress.

Frequently asked questions

What’s the shortest wordpress cron job no plugin setup?

Two hooks: wp_schedule_event to register the recurring event (inside an init callback, guarded by wp_next_scheduled so it only registers once), and a separate add_action for the event’s hook name that runs your actual function. Optionally a cron_schedules filter for custom intervals. That’s it — no plugin needed.

Why wrap wp_schedule_event in wp_next_scheduled?

wp_schedule_event registers the event every time it’s called, which fires on init on every request. Without the guard you’d queue thousands of duplicate events. wp_next_scheduled('your_hook') returns the timestamp of the next scheduled run, or false if none. Registering only when it’s false keeps the queue clean.

What are the built-in intervals?

WordPress ships hourly, twicedaily, daily, and weekly. To run more or less often, define a custom interval via the cron_schedules filter: return an array with your slug (e.g. '1hr_cron') mapping to ['interval' => 3600, 'display' => '1 Hour']. The interval is in seconds.

How do I clear a scheduled event I no longer want?

wp_clear_scheduled_hook('your_hook_name') removes every queued instance of that hook. Run it from a WP-CLI wp eval call or temporarily add it to functions.php, hit any page to fire init, then remove the line. For one-off dumps of the current queue, get_option('cron') returns the raw array.

Does wp-cron actually run on schedule?

No — WordPress’s built-in wp-cron.php only fires when someone visits the site. On low-traffic sites scheduled events can miss their window by hours. The fix is a real system cron job that hits wp-cron.php at a predictable interval — see how to set up a system-based cron job in WordPress.