Weight-Based Shipping Charges
You can calculate shipping charges based on the weight of the shippable items on the order in addition to the current baseline methods (flat fee, percentage of invoice, invoice amount range, custom). To use this method, on the Product Profile page click Edit on the Actions Bar, and enter the weight of the product in the weight field. This feature is available on Merchandise and Publication Products.
The shipping products now have two additional fields for the minimum and maximum weight. The Edit — Shipping — Price page is on shipping rates child form on the Shipping Profile page. The shipping rate will be determined based on the total weight of the shippable items being between the minimum and maximum weight ranges entered.
The amount you charge can be either a flat fee or percentage. To charge a flat fee, enter a price in the price field (above). To charge a percentage, enter a percentage amount in the percentage field (below). If you choose percentage, the amount will be calculated based on the order amount of the shippable items.
Once you have selected a method, the other field will be disabled. To enable it, clear the value in the field you have chosen. Any non-shippable items will be excluded from the percentage calculation.