Progressive flat rate based on the cart's subtotal percentage in WooCommerce

Question

In WooCommerce, I am trying to set a progressive shipping cost based on 10% of cart subtotal with $5 as minimum cost, up to $11 max cost.

Here is my code attempt:

add_filter( 'woocommerce_package_rates', 'woocommerce_package_rates', 10, 2 );
function woocommerce_package_rates( $rates, $package ) {
    // Make sure flat rate is available
    if ( isset( $rates['flat_rate:24'] ) ) {
        // Set the cost to $5
        $rates['flat_rate:24']->cost = 5;
    }
    $cart_subtotal = $WC()->cart->subtotal
    if ($cart_subtotal >50)

    $percentage = 0.10;  // Percentage (10%) in float
    $percentage_fee = ( WC()->cart->subtotal >+ WC()->cart->get_shipping_total()) * $percentage;
    }
 
    });
    return $rates;
}

This code gives a critical error on the website. I am quite new to Wordpress custom coding as you will probably tell from the code below.

Also I would like the displayed label to show "USPS" instead of "Flat rate".

For example, if the cart subtotal is $60, they would be charged $6 flat rate shipping cost (10% of subtotal).

What am I missing or doing wrong?

Answer 1

There are a lot of mistakes in your provided code… The following will allow you to set a shipping cost starting from 5$ to 11$ max, based on cart subtotal percentage.

First you need to set a cost of 5 (and also "UPS" as label) in your Flat rate settings.

Then use this code:

add_filter( 'woocommerce_package_rates', 'woocommerce_package_rates', 10, 2 );
function woocommerce_package_rates( $rates, $package ) {
    $max_cost   = 11; // Here set the max cost for the shipping method
    $percentage = 10; // Percentage to apply on cart subtotal
    $subtotal   = WC()->cart->get_subtotal(); // Cart subtotal without taxes

    // Loop through shipping rates
    foreach ( $rates as $rate_key => $rate ) {
        // Targetting specific flate rate shipping method
        if ( 'flat_rate:14' === $rate_key ) {
            $has_taxes = false;
            $base_cost = $rate->cost; // 5$ from this shipping method cost setting
            $new_cost  = $subtotal * $percentage / 100; // Calculation

            if( $new_cost > $base_cost ) {
                // 1. Rate cost
                if ( $new_cost < $max_cost ) {
                    $rates[$rate_key]->cost = $new_cost;
                    $rate_operand = $new_cost / $base_cost; // (for taxes if enabled)
                } else {
                    $rates[$rate_key]->cost = $max_cost;
                    $rate_operand = $max_cost / $base_cost; // (for taxes if enabled)
                }
                // 2. Taxes rate cost (if enabled)
                foreach ($rates[$rate_key]->taxes as $key => $tax){
                    if( $tax > 0 ){
                        // New tax calculated cost
                        $taxes[$key] = $tax * $rate_operand;
                        $has_taxes = true;
                    }
                }
                // Set new taxes cost
                if( $has_taxes ) {
                    $rates[$rate_key]->taxes = $taxes;
                }
            }
        }
    }
    return $rates;
}

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

Refresh the shipping caches:

1. This code is already saved on your functions.php file.
   
2. In a shipping zone settings, disable / save any shipping method, then enable back / save.
   
   You are done and you can test it.