The invoice price is not what the product costs you.

Landed cost is the total cost of a product once it is in your warehouse and ready to sell: unit price plus every cost required to get it there. Pricing or sourcing decisions made on the invoice price alone routinely understate true cost.

What belongs in the calculation

Product cost, freight, import duty, insurance, customs brokerage, port and handling fees, inspection costs and destination packaging all belong in landed cost. Domestic transfer to a fulfillment center after customs clearance is often forgotten but still counts.

Duty is a percentage of a different base

Import duty is typically charged on the customs value, which may differ from what you paid per unit depending on incoterms and declared value, not on your eventual landed cost. Get the correct HS code and duty rate for your product category rather than estimating from a similar item.

Spread cost across the whole shipment

Freight, insurance and brokerage are usually charged per shipment, not per unit. Divide these shared costs across every unit in that shipment, weighted by volume or value if units differ significantly in size, before adding them to per-unit product cost.

Use it to set a real price floor

Landed cost, not invoice price, is the correct base for your minimum viable selling price and for margin calculations that feed into break-even ROAS. A product that looks profitable on invoice price alone can be a loss-maker once duty and freight are included.