Long-run average total cost (LRATC) is a measure used to quantify the average cost associated with producing a certain level of output over a long period of time. Generally, LRATC is used to assess the cost-efficiency of a particular product, process, or business over a long-term basis. By providing a better picture of the overall cost associated with producing a certain output, LRATC also reveals more information about the company’s overall efficiency and ability to maintain production costs over the long-term.

To calculate LRATC, one must first determine the total costs associated with producing a specific output over a specific long-term period. This includes, but is not limited to, the fixed costs such as labor, materials, and other overhead, as well as the variable costs associated with production, such as supplies and energy. Next, the total cost must be divided by the total output produced over the same period of time. This reveals the LRATC, or average cost per unit of output. It is important to note that LRATC does not include non-production related costs, such as taxes and interest payments, as these are not directly associated with the production process.

LRATC can be used to identify inefficiencies in a certain product over the long-term. It is also used to illustrate how new investments in technologies and processes can potentially reduce LRATCs. This is because, in the long-term, businesses have far more flexibility to change their operations and processes in order to increase efficiency and reduce LRATC. For example, a company may invest in new technologies to increase production efficiency and reduce the cost of producing each unit of output.

As a result, LRATC can be used as an important tool to assess the performance of a business over the long-run. This is especially the case for businesses that produce items with wide or unpredictable demand, as LRATC allows for evaluation of the company’s overall efficiency over long periods of time. This can be very useful when it comes to analyzing the current and future value of a certain business or product.

Overall, LRATC is an invaluable tool for assessing a business' efficiency and cost-effectiveness in the long-term. By providing detailed information about the cost associated with producing certain outputs, LRATC allows businesses to accurately assess their cost-efficiency over a long period of time. This data can be used to identify inefficiencies and also to evaluate different investment options and production strategies. With this insight, companies can work to improve their performance and profitability over the long-term.