Greying out "out-of-stock" product variations with custom stock quantity reduction in WooCommerce

• Compare the total stock quantity to the newly added setting $multiplier
• Comment with explanation added to the code

function filter_woocommerce_variation_is_active( $active, $variation ) {        // Get multiplier    $multiplier = get_post_meta( $variation->get_variation_id(), '_stock_multiplier', true );           // NOT empty    if ( ! empty( $multiplier ) ) {        // Get stock quantity        $var_stock_count = $variation->get_stock_quantity();                // Stock quantity < multiplier        if( $var_stock_count < $multiplier ) {            $active = false;        }    }        return $active;}add_filter( 'woocommerce_variation_is_active', 'filter_woocommerce_variation_is_active', 10, 2 );

It doesn't work because:

• $item variable is not defined in your code.
• your custom field is defined in the parent variable product.

So you need to replace:

$multiplier = $item->get_product()->get_meta( '_stock_multiplier' );

by the folling (getting the data from the parent variable product):

$multiplier = get_post_meta( $variation->get_parent_id(), '_stock_multiplier', true );

So in your code:

add_filter( 'woocommerce_variation_is_active', 'my_jazzy_function', 10, 2 ); function my_jazzy_function( $active, $variation ) {        // Get multiplier    if( $multiplier = get_post_meta( $variation->get_parent_id(), '_stock_multiplier', true ) {        // Get stock quantity        $var_stock_count = (int) $variation->get_stock_quantity();            // if there are 5 or less, disable the variant, could always just set to 0        return $var_stock_count <= $multiplier ? false : $active;    }    return  $active;}

It should work now.