Woocommerce Progressive extra cost based on total number of items in the cart

I am looking for some code which can make an extra charge based on the total number of items in the cart like:

• If number of items in cart is > 6 ===> extra cost = 5
• If number of items in cart is > 12 ==> extra cost = 10

I have tried this code, but I can’t get it working for my case.

How can I make an extra cost based on total number of items in the cart?

Answer

Based on (this answer) WooCommerce Cart Quantity Base Discount, you can add a progressive fee based on total number of items:

add_action( 'woocommerce_cart_calculate_fees','woocommerce_cart_extra_cost', 10, 1 );
function woocommerce_cart_extra_cost( $cart ) {
    if ( is_admin() && ! defined( 'DOING_AJAX' ) )  return;

    $cart_item_count = $cart->get_cart_contents_count();

    // CONDITIONAL ITEMS QUANTITY FEE AMOUNT
    if( $cart_item_count < 6 )
        $fee = 0;
    elseif( $cart_item_count >= 6 && $cart_item_count < 12 )
        $fee = 5;
    elseif( $cart_item_count >= 12 )
        $fee = 10;

    if( $fee > 0 )
        $cart->add_fee( __( "Extra Cost", "woocommerce" ), $fee, true);
}

Code goes in functions.php file of your active child theme (or theme) or also in any plugin file.

Tested and works.