The supplier's unit price isn't what a unit actually costs you. Freight, customs duty and other shipment fees all land on top of it — this spreads them across the shipment to get a real per-unit cost.
Landed cost calculator
Customs duty here is calculated as a % of total product cost (unit cost × quantity), which is how it's assessed for most shipments — check your product's actual duty rate with a broker or your country's tariff schedule if you're not sure of it.
Freight and duty don't scale down with small orders the way the unit price does — a $1,800 freight bill on a 2,000-unit shipment is $0.90 a unit, and a 6% duty rate adds another $0.25. Add a few hundred dollars in broker and handling fees and a $4.20 unit is quietly a $5.50+ landed cost before it's even in your warehouse.
That gap matters most when it's missing from margin and pricing decisions. If cost of goods is set from the supplier's unit price alone, every margin, break-even ROAS and profitability number built on top of it is optimistic — sometimes by 20-30%. Landed cost is the number that belongs in those calculations instead: use it as "cost per order" in the break-even ROAS calculator, or as the cost basis when setting retail price.
Freight and fees also don't move in a straight line with order size — a bigger shipment usually has a lower per-unit freight cost, which is one of the real reasons volume orders (and hitting a supplier's minimum order quantity) can lower landed cost even when the unit price doesn't change. See the MOQ calculator for whether a bigger order is actually worth the extra cash tied up.