You can calculate the shipping fee based on the the total weight of the products ordered. Setup unit weight for each product You can set up the unit weight for the products. In the Neartail Edit page, click on the product to select it > click on the gear icon for that product > Product settings page will be displayed > click Advanced > enable Shipping, enter the unit weight for the product and click Save. Repeat the steps for all the products. Calculate total weight In the Neartail Edit page, click on the Order Quantity field to select it > click on the Add field icon > a new field will be added below the selected Order Quantity field > enter the title Total Weight, select Short answer question > click on the settings gear icon for this field > Field settings page will be displayed > click Answer > enter the formula WEIGHT() in the Calculate option and click Save. Calculate shipping fee In the Neartail Edit page, click on the Add price field button > select Delivery fee, click Next > select Custom calculation, click Next > Enter the formula below and click Create. Total Weight * 40 Calculate total amount In the Edit page, click on the Add price field button > select Net amount, click Next > select Standard calculation using NETTOTAL() formula, click Next > click Create. Please try this and confirm.