Create a simple shortcode to output the Woocommerce cart count

cart-count-shortcode.php

<?php

// Add cart count shortcode [cart_count]
// =============================================================================

add_shortcode( 'cart_count', 'mb_cart_count' );
function mb_cart_count() {
    if ( class_exists( 'WooCommerce' ) && function_exists( 'WC' ) ) { // Check for WooCommerce and WC() function.
        if ( ! WC()->cart->is_empty() ) {
            return (string) WC()->cart->get_cart_contents_count(); // Cast to string for consistency.
        }
        return '0';
    }
    return '';
}

@KZeni Good call, you found an old one here :)