It is also called per-unit cost or average cost per unit. A service business can apply the same idea to one unit of service, such as one order shipped or one hour billed.
Businesses use unit cost to set a price floor, check the margin on each sale and compare suppliers or production runs. For an ecommerce seller, the useful version goes past the factory price: each unit also picks up freight, duty and fulfillment fees on its way to a customer, which the breakdown below walks through.
How Do You Calculate Unit Cost?
Add up the fixed and variable costs for one production run, purchase order or period, then divide by the units made or bought in that same run:
Unit cost = (total fixed costs + total variable costs) / number of units
- Pick the run. Choose one production run, purchase order or month, and count every unit in it.
- Total the fixed costs. These stay the same whatever the volume in that run: setup and tooling, rent, salaried staff.
- Total the variable costs. These rise with each unit: materials, components, packaging, piece-rate labor.
- Divide by the units. The result is the average cost of one unit in that run.
Example: a company makes 10,000 units in a month. Its fixed costs are $5,000 and its variable costs are $15,000 ($1.50 a unit). Unit cost = ($5,000 + $15,000) / 10,000 = $2.00 per unit.
Fixed vs. Variable Costs: Why Unit Cost Changes With Volume
The two kinds of cost behave differently once you divide them by units. Variable cost per unit stays about the same however many units you make, because each unit brings its own materials. Fixed costs stay the same in total, so the fixed share of each unit shrinks as volume grows. That is why unit cost usually falls as a run gets bigger, the effect behind economies of scale.
Example, with the same $5,000 of fixed costs and $1.50 of variable cost per unit:
- 5,000 units: ($5,000 + $7,500) / 5,000 = $2.50 per unit
- 10,000 units: ($5,000 + $15,000) / 10,000 = $2.00 per unit
- 20,000 units: ($5,000 + $30,000) / 20,000 = $1.75 per unit
The same arithmetic sits behind a supplier's minimum order quantity (MOQ): a factory needs enough units to spread its setup cost, and bigger orders often get a lower price per unit. Ordering more lowers unit cost, but it also ties up cash in stock and adds storage, so the cheapest unit is not always the cheapest order.
Types of Unit Cost
- Variable cost per unit: total variable costs divided by units. It stays roughly constant per unit, while the total moves with volume.
- Fixed cost per unit: total fixed costs divided by units. The total stays constant, so the amount per unit falls as volume rises.
- Total (average) unit cost: fixed plus variable cost per unit, the figure the formula above gives.
- Marginal cost: the extra cost of making one more unit. When no new fixed cost is needed, it is close to the variable cost per unit.
Unit Cost vs. Unit Price
Unit cost is what one unit costs the business. Unit price is what one unit sells for. The gap between them is the margin on each unit before overhead.
Example: a unit costs $2.00 to make and sells to a retailer for $3.50, leaving $1.50 per unit, about 43% of the price.
On a store shelf, "unit price" has a second meaning: the selling price per standard measure, such as per ounce, per pound or per item, so shoppers can compare package sizes.
How to Calculate the Total Unit Cost of an Ecommerce Product
For a business that buys finished goods and sells them online, the factory price is only the first line. Each unit also carries a share of the freight that brought it in, any customs duty, and the cost of storing, packing and shipping it. Two totals matter.
The first is landed cost: product cost plus inbound freight, duty and the other charges to get the goods into your warehouse. It is the basis of the inventory cost on your books. For goods bought during the year, IRS Publication 538 says cost "means the invoice price minus appropriate discounts plus transportation or other charges incurred in acquiring the goods."
The second is the fulfilled cost per unit: landed cost plus the fulfillment fees and outbound shipping for each order. Those costs come after the goods are acquired, so they sit outside landed cost, but they belong in the number you compare with your price.
Example: a seller imports 2,000 units of one stock keeping unit (SKU) and ships every order as a single unit.
- Product cost: $16,000 for 2,000 units = $8.00 per unit
- Inbound freight: $1,800 for the shipment = $0.90 per unit
- Customs duty: $960, at an example rate of 6% on $16,000 of goods (the real rate depends on the product's tariff classification) = $0.48 per unit
- Landed cost: $9.38 per unit
- Receiving and storage at a fulfillment provider: $400 while the batch sells = $0.20 per unit
- Pick, pack and packaging: $3.15 per order
- Outbound shipping: $6.50 per order
- Fulfilled cost: $19.23 per unit sold
At a unit price of $34.99, that leaves $15.76 per unit before marketing, payment fees, returns and overhead. Pricing from the $8.00 factory cost alone would have overstated that margin by $11.23 a unit. Fulfillment fees differ by provider and by order profile: the 3PL pricing guide explains each fee type, and the fulfillment cost calculator estimates them per order.
How Businesses Use Unit Cost
- Pricing: the fulfilled cost per unit is the floor. Price below it and each sale loses money even before overhead.
- Break-even volume: price minus variable cost per unit is what each sale contributes toward fixed costs, and break-even analysis divides fixed costs by that amount. Example: $5,000 of fixed costs, a $3.50 price and $1.50 of variable cost per unit break even at 2,500 units.
- Inventory value: when purchase orders land at different unit costs, the weighted average cost of inventory blends them into one cost per unit. Example: 1,000 units at $9.38 and 1,000 units at $10.10 average $9.74 each.
- Customer and channel profit: a single-unit online order and a wholesale case of the same product cost different amounts to deliver. Cost-to-serve analysis applies unit-cost thinking to each customer or channel.