In order to calculate the Amazon FBA profit margin for your product, follow the below steps:
(You can use any currency of your choice when using this calculator)
1. Enter the total number of product units, that you ordered from your supplier
2. Enter the buying price of product unit, that is buying price from your supplier
3. Enter the total shipping fees, that is the total shipping cost associated with shipping, including customs charges or any other charges, from supplier to Amazon warehouse
4. Enter the unit price of your product that you want to sell on Amazon

There are no specific steps are required to calculate the total landed cost, landed cost per unit and total product cost per unit. All of the them will be calculated automatically.

You can contact here for any further queries.

You can use this Amazon Sales Estimator to calculate the number of sales on Amazon.