Slug Field

A text input that automatically formats its value as a URL-safe slug. Can mirror another ACF field in real time — type a title and the slug updates instantly. Supports hyphen or underscore separators, optional uppercase, max length, and a uniqueness warning.

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Pro field

Slug Field requires the Extra Fields for ACF Pro license.

Settings

Setting	Default	Options	Description
Sync From	(empty)	ACF field name	Name of another ACF field to mirror as a slug in real time (e.g. `title`).
Allow Uppercase	`false`	on/off	Allow uppercase letters. Off = forces lowercase.
Separator	`-`	`-` · `_`	Character used to replace spaces and special characters.
Max Length	`0`	Integer	Maximum character count. `0` = unlimited.
Uniqueness Check	`false`	on/off	Warn the editor if the entered slug already exists in the database.

Return values

Returns the slug string exactly as stored.

$slug = get_field('product_slug');
// "my-awesome-product"

$slug = get_field('db_key'); // separator: _, allow_uppercase: true
// "My_Awesome_Key"

Usage

Building a custom permalink

$post_slug = get_field('custom_slug');

if ($post_slug) {
    $base_url = home_url('/products/');
    $url = $base_url . rawurlencode($post_slug) . '/';

    echo '<a href="' . esc_url($url) . '">' . esc_html(get_the_title()) . '</a>';
}

Generating a CSS class or HTML ID

$section_slug = get_field('section_id');

if ($section_slug) {
    echo '<section id="' . esc_attr($section_slug) . '" class="section">';
}

Rewrite rule from ACF slug

$custom_base = get_field('archive_slug', 'option');

if ($custom_base) {
    add_rewrite_rule(
        $custom_base . '/([^/]+)/?$',
        'index.php?post_type=product&name=$matches[1]',
        'top'
    );
}

Using in a WP_Query

$slug = get_field('linked_category_slug');

if ($slug) {
    $term = get_term_by('slug', $slug, 'category');
    if ($term) {
        $posts = get_posts([
            'category' => $term->term_id,
        ]);
    }
}

✓

Sync From field name

The Sync From setting takes the ACF field name (not the label). Find it in the field's settings under "Field Name" — it's the snake_case identifier like product_title.