What is the formula for calculating the delivery of parcels across the ocean?

Question

Mathematics

Hello!
Maybe someone knows or has come across what is the formula for calculating the delivery of parcels across the ocean? Or where to turn with this question?
Here, for example , there is a calculator:
If you select the "Ocean" method, specify where and where, as well as the type of product (it doesn't matter to me which one) and its cost (it also doesn't matter), then the cost is calculated, but by what formula?