Per-unit cost is a term used to describe the cost of a single unit of a product or service. It is calculated by dividing the total cost of a product or service by the number of units purchased. This calculation is useful for comparing the cost of different products or services, as it allows for an apples-to-apples comparison of the cost of each unit. The RATE of per-unit cost is often used in business and economics to determine the profitability of a product or service.