Shipping cost based on cart total weight in Woocommerce 3

In my Woocommerce Webshop I do have different Products. I would like to have shipping cost calculated on total cart items weight:

• from 0 to 6 Kilos the cost is 5 €,
• from 6 to 12 Kilos the cost is 9 €

Actually if I have a Product which is 1 Kilo the shipping cost is 5 €, but if I have 10 items of this product in my basket, the shipping fee is still 5 € (and it should be 9 € instead).

How can I have a progressive shipping cost based on cart total weight?

Answer

Try the following function which “Flat Rate” cost will be changed based on cart total weight.

Using “Flate rate” shipping method, you will need to set a reference shipping cost with a simple initial cost instead of any formula. It can be for example 1. This cost will be replaced by my answer code, dynamically based on cart total weight.

You may have to “Enable debug mode” in general shipping settings under “Shipping options” tab, to disable temporarily shipping caches.

add_filter('woocommerce_package_rates', 'shipping_cost_based_on_weight', 12, 2);
function shipping_cost_based_on_weight( $rates, $package ){
    if ( is_admin() && ! defined( 'DOING_AJAX' ) )
        return $rates;

    // HERE define the differents costs
    $cost1 = 5; // Up to 6 Kg
    $cost2 = 9; // Above 6 Kg and below 12 kg
    $cost3 = 9; // Above 12 kg

    // The cart total Weight
    $total_weight = WC()->cart->get_cart_contents_weight();

    // Loop through the shipping taxes array
    foreach ( $rates as $rate_key => $rate ){
        $has_taxes = false;
        // Targetting "flat rate"
        if( 'flat_rate' === $rate->method_id ){
            // Get the initial cost
            $initial_cost = $new_cost = $rates[$rate_key]->cost;

            // Calculate new cost
            if( $total_weight <= 6 ) { // Below 6 Kg
                $new_cost = $cost1;
            }
            elseif( $total_weight > 6 && $total_weight <= 12 ) { // Between 6 and 12 Kg
                $new_cost = $cost2;
            }
            else { // Above 12 Kg
                $new_cost = $cost3;
            }

            // Set the new cost
            $rates[$rate_key]->cost = $new_cost;

            // Taxes rate cost (if enabled)
            $taxes = [];
            // Loop through the shipping taxes array (as they can be many)
            foreach ($rates[$rate_key]->taxes as $key => $tax){
                if( $rates[$rate_key]->taxes[$key] > 0 ){
                    // Get the initial tax cost
                    $initial_tax_cost = $new_tax_cost = $rates[$rate_key]->taxes[$key];
                    // Get the tax rate conversion
                    $tax_rate    = $initial_tax_cost / $initial_cost;
                    // Set the new tax cost
                    $taxes[$key] = $new_cost * $tax_rate;
                    $has_taxes   = true; // Enabling tax
                }
            }
            if( $has_taxes )
                $rates[$rate_key]->taxes = $taxes;
        }
    }
    return $rates;
}

Code goes in function.php file of your active child theme (or active theme). Tested and works.

Once tested, don’t forget to disable “Enable debug mode” option in shipping settings.