Hi!
For example
1. Create an ACF field (price_per_kilo) for Product.
2. In Woo template use something like this
global $product;
$price = $product->get_price();
$weight = $product->get_weight();
$id = $product->get_id();
$value = 1000 * $price / $weight;
update_field('price_per_kilo', $value, $id); // this code updates data for this field
the_field('price_per_kilo', $product->$id ); //show price per kilo