This popular shipping pricing scheme charges a flat fee for orders up to a certain weight. Orders that exceed that weight limit will have an additional fee based on how far over the limit the weight is. In this example, the shop owner is charging an €18 fee for orders up to 15kg. Orders above 15kg are charged an extra €1 for each additional kg.

There are multiple cost options in this method, and each row is allowed one or more of these costs. However, each cost type is applied to the entire order, so setting up the incremental fee will need to account for that. The first thing to note is that there are two possible cost calculations for this option, so our table is going to need two rows. The first row is for the flat fee, and the second row is for the flat fee plus the incremental fee. The image below shows this scenario already setup:

The first row is the simplest. It has one condition and one cost. The condition checks the order’s weight to determine if it is less than or equal to 15kg. If it is, the customer qualifies for the flat €18.00 fee. The second row checks if the order is greater than 15kg. Orders that meet this criteria will have two costs applied. The ‘for every’ cost type adds a €1.00 charge for every kilogram in the order, not just the excess weight. This is why the flat fee in this row is only €3.00.

Let’s assume the customer has added 18.75kg of product to their order. For the incremental cost, that would be the equivalent of 19kg, and thus a €19 charge. The shipping model is €18 for the first 15kg, and €1.00 there after. That would mean a total cost of €22 for an order of 19kg. The difference between our desired cost (€22) and the ‘for every kg’ cost (€19) is €3. So the flat rate of €3 is added to adjust for this difference.

## Using Negative Fees

In some cases, the base rate may actually be less than what the incremental cost returns. In a similar scenario as above, a shop owner may charge €10 for orders up to 15kg, and €1.00 for each kg thereafter. The per kilogram cost of a 15kg order would be €15, which is €5 too high. For instances like this, the settings fields accept negative numbers. The image below illustrates how a configuration would look with a negative value.