I have products that depending on manufacturers or materials could have some fixed costs.

These costs must be added ONLY to the final price.


  • I want to buy 100 cotton shirts and the cost of each shirt is 1 (one) dollar.
  • My final cost is 100 x 1 dollar = 100 dollars.
  • At this final cost I have to add 30 dollars as "start of work" cost, a cost to apply to final cost and not to each single shirt.

Is the $30 constant, meaning $30 for 100 shirts, but what about 10 shirts, still $30?

So I have two different type of costs:

1. The first one related to quantity

  • from 1 to 100 shirts: 0.50$ additional cost for each shirt
  • from 101 to 200 shirts: 0.40$ additional cost for each shirt
  • from 201 to 300 shirts: 0.30$ additional cost for each shirt and so on.

2. The second one is a fixed cost (for example: 30$ even if the shirts are 100 or 10)

I created some custom fields as cart variant but I can't create exactly what I want.

Adding fixed costs to product shopping cart page

For a final fixed charge use a Tax/Calculation rule set to

  • Price modifier before tax per bill,
  • Maths operation +
  • with the Value as the surcharge to be applied.

This can be applied to single or multiple categories and/or manufacturer as required.

Use multiple instances if required.

The extra charge will only be shown in the cart at checkout.

I added a new rule to the final bill amount and all goes well.