load_theme_textdomain( string $domain, string|false $path = false ): bool

Loads the theme’s translated strings.


If the current locale exists as a .mo file in the theme’s root directory, it will be included in the translated strings by the $domain.

The .mo files must be named based on the locale exactly.


Text domain. Unique identifier for retrieving translated strings.
Path to the directory containing the .mo file.



bool True when textdomain is successfully loaded, false otherwise.


function load_theme_textdomain( $domain, $path = false ) {
	/** @var WP_Textdomain_Registry $wp_textdomain_registry */
	global $wp_textdomain_registry;

	 * Filters a theme's locale.
	 * @since 3.0.0
	 * @param string $locale The theme's current locale.
	 * @param string $domain Text domain. Unique identifier for retrieving translated strings.
	$locale = apply_filters( 'theme_locale', determine_locale(), $domain );

	$mofile = $domain . '-' . $locale . '.mo';

	// Try to load from the languages directory first.
	if ( load_textdomain( $domain, WP_LANG_DIR . '/themes/' . $mofile, $locale ) ) {
		return true;

	if ( ! $path ) {
		$path = get_template_directory();

	$wp_textdomain_registry->set_custom_path( $domain, $path );

	return load_textdomain( $domain, $path . '/' . $locale . '.mo', $locale );


apply_filters( ‘theme_locale’, string $locale, string $domain )

Filters a theme’s locale.


4.6.0The function now tries to load the .mo file from the languages directory first.

User Contributed Notes

  1. Skip to note 3 content

    1st example
    The load_theme_textdomain() function should generally be called from within the after_setup_theme action hook.

    add_action('after_setup_theme', 'wpdocs_theme_setup');
     * Load translations for wpdocs_theme
    function wpdocs_theme_setup(){
        load_theme_textdomain('wpdocs_theme', get_template_directory() . '/languages');

    The .mo files must use language-only filenames, like languages/de_DE.mo in your theme directory.

    Unlike plugin language files, a name like my_theme-de_DE.mo will NOT work. Although plugin language files allow you to specify the text-domain in the filename, this will NOT work with themes. Language files for themes should include the language shortcut ONLY.

  2. Skip to note 4 content

    2nd example
    you can use this example if you wish to switch theme language using a variable passed within the URL, for example to load the Tamazikht language, your URL would look like; www.example.com/?l=tz_MA, this will search for a .mo file with name tz_MA.mo in the language directory inside your theme.

    // must be called before load_theme_textdomain()
    add_filter( 'locale', 'wpdocs_theme_localized' );
     * Switch to locale given as query parameter l, if present
    function wpdocs_theme_localized( $locale )
    	if ( isset( $_GET['l'] ) )
    		return sanitize_key( $_GET['l'] );
    	return $locale;
    // Theme translations can be filed in the my_theme/languages/ directory
    // WordPress translations can be filed in the wp-content/languages/ directory
    load_theme_textdomain( 'wpdocs_theme_textdomain', get_template_directory().'/languages' );

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