What is the term for the difference between a buyer's reservation price and the actual price paid?

The term that accurately describes the difference between a buyer's reservation price and the actual price paid is consumer surplus. Consumer surplus represents the benefit consumers receive when they are able to purchase a product for less than the maximum price they are willing to pay, which is their reservation price. This concept is a key element in understanding how markets function and how consumer satisfaction can be quantified.

When consumers have a reservation price that exceeds the market price, they gain surplus because they are able to purchase the good at a lower price than expected. This difference reflects the value they place on the product over and above what they actually pay, highlighting the additional utility or satisfaction derived from the transaction.

While "buyer's surplus" might intuitively seem like a fitting description, the more widely accepted and standardized term in economics is "consumer surplus." Other terms like "expected surplus" and "market surplus" do not specifically pertain to the concept of benefits derived from purchasing goods at a price below the reservation price, making them less relevant in this context. Therefore, the most appropriate term is consumer surplus, which captures this economic phenomenon accurately.