To calculate your fees, you would first need to understand the Amazon Fulfillment options available to you, and choose which one you would be using for your products. Many sellers choose combinations of fulfillment options.
Amazon stores, packs & delivers your products to the customers
You store & pack your products, Amazon delivers it to your customers
You store, pack & deliver your products to your customers
After this, you can go about calculating your approximate fees for your product.